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    <div class="os1">9.3 关联容器：QMap、QMultiMap</div>
    <br>
    本节介绍两种基于红黑树的关联容器，单映射 QMap、多映射 QMultiMap。
    前面介绍的顺序容器通常存储大量连续序号的元素，而关联容器则存储离散的“不正常序号”的元素。 数组和顺序容器的序号都是从 0
    开始，逐渐递增，而关联容器没有正常的序号， 单映射和单哈希映射通过重载中括号[]运算符函数，它们的元素序号可以是各种奇葩的数值类型，
    比如用字符串、图片、颜色、日期、字体等数据作为序号，像 map["红色"] = 0xFF0000 就是单映射的例子。 本节分为两个小节内容，依次介绍
    QMap、QMultiMap ，并各安排一个示例使用这些关联容器。 <br>
    <br>
    <div class="os2">9.3.1 单映射 QMap </div>
    <br>
    QMap 模板类通常将数据按照 key - value（键-值） 配对的形式存储，程序中以 key 作为序号来查询对应的 value，比如&nbsp;
    map["红色"] = 0xFF0000 。QMap 通常将一个 key 映射为一个 value，而 QMultiMap 通常将 一个 key
    映射为多个 value，这就是单映射和多映射的区别。<br>
    QMap 模板类 key 和 value 的类型可以是C++和Qt常用的数据类型，也可以使用自定义类型，<b>但是注意key 和 value
      都必须是可赋值类型！</b><br>
    QMap 使用红黑树存储 key - value 配对数据（ 一对 key - value 后文统称为映射中一个元素，或者红黑树的一个节点），排序时按照
    key 来比较大小，因此对 key 类型有额外要求：<br>
    <b>key 类型必须提供全局的双参数&nbsp; operator&lt;()&nbsp; 比较数值大小。</b><br>
    <br>
    下面我们分类列举QMap模板类的功能函数：<br>
    （1）构造函数<br>
    <div class="code">&nbsp;&nbsp;&nbsp; QMap()&nbsp; //默认构造函数<br>
      &nbsp;&nbsp;&nbsp; QMap(std::initializer_list&lt;std::pair&lt;Key, T&gt;
      &gt; list) //初始化列表构造函数<br>
      &nbsp;&nbsp;&nbsp; QMap(const QMap&lt;Key, T&gt; &amp; other) //复制构造函数<br>
      &nbsp;&nbsp;&nbsp; QMap(QMap&lt;Key, T&gt; &amp;&amp; other)&nbsp;&nbsp;
      //移动构造函数<br>
      &nbsp;&nbsp;&nbsp; QMap(const std::map&lt;Key, T&gt; &amp; other)
      //根据标准库的映射构造 QMap<br>
      &nbsp;&nbsp;&nbsp; ~QMap() //析构函数</div>
    最常用是默认构造函数，注意使用模板类时要带 key 和 value&nbsp; 的类型，例如定义姓名和年龄的映射：<br>
    <div class="code">QMap&lt;QString, int&gt; nameAge;</div>
    QString 作为 key 类型，保存姓名，int 作为 value 类型，保存年龄。<br>
    C++11特性支持初始化列表构造和移动构造，比如：<br>
    <div class="code">&nbsp;&nbsp;&nbsp; QMap&lt;QString, int&gt; nameAge{
      {"Alice", 20},<br>
      &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      {"Bob", 22},<br>
      &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      {"Cell", 19} };<br>
      &nbsp;&nbsp;&nbsp; qDebug()&lt;&lt;nameAge;<br>
      &nbsp;&nbsp;&nbsp; QMap&lt;QString, int&gt; nameAgeOther = std::move(
      nameAge );<br>
      &nbsp;&nbsp;&nbsp; qDebug()&lt;&lt;nameAge;<br>
      &nbsp;&nbsp;&nbsp; qDebug()&lt;&lt;nameAgeOther;</div>
    上面一段代码的输出如下所示：<br>
    <div class="output"> QMap(("Alice", 20)("Bob", 22)("Cell", 19))<br>
      QMap()<br>
      QMap(("Alice", 20)("Bob", 22)("Cell", 19))<br>
    </div>
    <br>
    移动构造函数会将 nameAge 内所有元素都转移给 nameAgeOther，因此 nameAge 最后变成空的，而 nameAgeOther
    会包含原本 nameAge 拥有的元素。<br>
    <br>
    std::map 是标准库的映射模板类，包含在 &lt;map&gt; 头文件中，使用方法与 QMap 类似，如果需要从标准库的 map 构造 QMap
    对象，可以参照下面代码编写：<br>
    <div class="code">&nbsp;&nbsp;&nbsp; std::map&lt;QString , int&gt;&nbsp;
      astdMap{ {"Alice", 20},<br>
      &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      {"Bob", 22},<br>
      &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      {"Cell", 19} };<br>
      &nbsp;&nbsp;&nbsp; QMap&lt;QString, int&gt; nameAge( astdMap );</div>
    注意 std::map 和 QMap 的 key、value 类型必须要一致，才能这样构造。<br>
    <br>
    （2）添加函数<br>
    本小节的元素是指一对 key - value ，添加元素后，QMap 内部的红黑树会新加一个节点。<br>
    向 QMap 添加新元素有三种方式，第一种通过两个 insert()&nbsp; 函数：<br>
    <div class="code">iterator&nbsp;&nbsp;&nbsp; insert(const Key &amp; key,
      const T &amp; value) //直接插入一对 key - value<br>
      iterator&nbsp;&nbsp;&nbsp; insert(const_iterator pos, const Key &amp; key,
      const T &amp; value)//在建议的迭代器 pos 位置插入一对 key - value</div>
    第一个 insert() 函数不关心元素插入位置，直接添加到红黑树中；<br>
    第二个 insert() 函数是建议在迭代器 pos 位置插入元素，但是建议的位置不一定有效，红黑树是按照 key
    大小排序的，实际插入的位置是按照排序规则确定的，pos 位置不一定有效，所以一般插入元素推荐用第一个 insert() 函数。<br>
    <br>
    向 QMap 添加新元素第二种方式，就是运算符重载函数 operator[]() ：<br>
    <div class="code">T &amp; QMap::​operator[](const Key &amp; key)</div>
    上面两种插入元素方式举例：<br>
    <div class="code">&nbsp;&nbsp;&nbsp; QMap&lt;QString, int&gt; nameAge;<br>
      &nbsp;&nbsp;&nbsp; nameAge.insert( "Alice", 20 );<br>
      &nbsp;&nbsp;&nbsp; nameAge["Bob"] = 22;<br>
      &nbsp;&nbsp;&nbsp; nameAge["Cell"] = 19;</div>
    中括号的方式用起来更像数组，语法也相对简单一些。<b><br>
      如果 key - value 配对已经存储在映射对象里面了，那么继续用相同 key 调用 insert() 或 operator[]() ，<br>
      由于单映射的特性，结果就是 key 不变，而 key 对应的 value 会被新的 value 覆盖。</b><br>
    <b> insert() 或 operator[]() 在映射对象里没有 key 时添加新元素，而当已存在 key 时用新value覆盖旧的value。</b><br>
    <br>
    向 QMap 添加新元素的第三种方式是 insertMulti() 函数，即红黑树会插入一对多映射节点，放到后面介绍，一般不建议使用。<br>
    <br>
    （3）移除和删除函数<br>
    从映射对象卸下一个元素，但不释放空间，使用下面函数：<br>
    <div class="code">T&nbsp;&nbsp;&nbsp; take(const Key &amp; key)</div>
    返回值 T 是 value 类型的数值。如果映射对象里根本没有指定 key，那么返回值是 value 类型默认构造函数生成的对象。<br>
    如果不需要返回值，直接从映射对象删除指定 key 及其 value，使用下面函数：<br>
    <div class="code">int&nbsp;&nbsp;&nbsp; remove(const Key &amp; key)</div>
    返回值是删除元素的个数，如果返回值为 0，说明映射里没有该 value；如果为 1 ，说明正好删除了一对 key - value
    ；如果返回值大于1，说明程序之前使用 insertMulti() 函数为一个 key 添加了多个 value 值（QMap 允许一对多映射，多个
    key-value 元素 的 key 值相同，但一般不建议这样做）。<br>
    如果希望清空所有元素，那么使用如下函数：<br>
    <div class="code">void&nbsp;&nbsp; &nbsp;clear()<br>
    </div>
    <br>
    （4）访问和查询函数<br>
    查询映射对象内是否包含 key 键：<br>
    <div class="code">bool&nbsp;&nbsp; &nbsp;contains(const Key &amp; key) const</div>
    查询映射对象内所有元素数目：<br>
    <div class="code">int&nbsp;&nbsp; &nbsp;count() const<br>
      int&nbsp;&nbsp;&nbsp; size() const</div>
    统计 key 对应的 value 值数量，使用下面函数：<br>
    <div class="code">int&nbsp;&nbsp; &nbsp;count(const Key &amp; key) const</div>
    如果映射对象不存在 key 键，那么返回值为 0，如果存在一对 key-value ，那么返回值为 1；如果程序之前使用 insertMulti()
    函数为一个 key 添加了多个 value，那么返回值是多个 value 值的数量。<br>
    判断映射对象是否全空，没有元素，使用下面两个函数都可以：<br>
    <div class="code">bool&nbsp;&nbsp; &nbsp;empty() const&nbsp; &nbsp; &nbsp;
      //STL风格<br>
      bool&nbsp;&nbsp;&nbsp; isEmpty() const&nbsp;&nbsp; //Qt风格</div>
    <br>
    获取映射中第一个 value 值，使用下面函数：<br>
    <div class="code">T &amp;&nbsp;&nbsp;&nbsp; first()<br>
      const T &amp;&nbsp;&nbsp;&nbsp; first() const</div>
    获取映射中第一个 key 键，使用下面函数：<br>
    <div class="code">const Key &amp;&nbsp;&nbsp;&nbsp; firstKey() const</div>
    获取映射中最后一个 value 值，使用下面函数：<br>
    <div class="code">T &amp;&nbsp;&nbsp;&nbsp; last()<br>
      const T &amp;&nbsp;&nbsp;&nbsp; last() const</div>
    获取映射中最后一个 key 键，使用下面函数：<br>
    <div class="code">const Key &amp;&nbsp;&nbsp;&nbsp; lastKey() const</div>
    <br>
    根据已知 value 值反查归属的 key 键：<br>
    <div class="code">const Key&nbsp;&nbsp;&nbsp; key(const T &amp; value, const
      Key &amp; defaultKey = Key()) const</div>
    反查耗时比较长，需要逐个遍历元素，注意多个 key 对应的 value 可能一样，所以上面函数只返回第一个匹配的 key。如果找不到就返回默认构造的
    Key() 。<br>
    如果要根据 value 反查所有匹配的 key 键列表，使用下面函数：<br>
    <div class="code">QList&lt;Key&gt;&nbsp;&nbsp;&nbsp; keys(const T &amp;
      value) const</div>
    如果需要获取映射所有元素的 key 值列表，使用下面函数：<br>
    <div class="code">QList&lt;Key&gt;&nbsp;&nbsp;&nbsp; keys() const</div>
    注意 insertMulti() 函数可能导致多个 key-value 元素的 key 值一样，keys()
    获取的键值是可能重复的。如果希望获取不重复出现的 key 列表，使用下面函数：<br>
    <div class="code">QList&lt;Key&gt;&nbsp;&nbsp;&nbsp; uniqueKeys() const</div>
    根据 key 查询对应 value ，使用下面函数：<br>
    <div class="code">const T&nbsp;&nbsp;&nbsp; value(const Key &amp; key, const
      T &amp; defaultValue = T()) const</div>
    如果没有找到 key-value 元素，那么返回 T() 值，就是 value 类型默认构造值。<br>
    存在一对多映射的情况下，可以用下面函数获取 key 对应的多个 value 值列表：<br>
    <div class="code">QList&lt;T&gt;&nbsp;&nbsp;&nbsp; values(const Key &amp;
      key) const</div>
    如果要获取映射中所有元素的 value 值列表，使用下面函数：<br>
    <div class="code">QList&lt;T&gt;&nbsp;&nbsp;&nbsp; values() const</div>
    <br>
    （5）交换函数<br>
    将映射对象自身的元素与另一个映射对象中的元素全部互换，使用下面函数：<br>
    <div class="code">void&nbsp;&nbsp; &nbsp;swap(QMap&lt;Key, T&gt; &amp;
      other)</div>
    swap() 函数效率非常高，并且从不失败。<br>
    <br>
    （6）运算符函数<br>
    对于运算符函数，我们以下面两个映射来举例说明：<br>
    <div class="code">&nbsp;&nbsp;&nbsp; QMap&lt;QString, int&gt; m1;<br>
      &nbsp;&nbsp;&nbsp; m1["Alice"] =&nbsp; 20;<br>
      &nbsp;&nbsp;&nbsp; QMap&lt;QString, int&gt; m2;<br>
      &nbsp;&nbsp;&nbsp; m2["Bob"] = 22;<br>
      &nbsp;&nbsp;&nbsp; m2["Cell"] = 19;</div>
    运算符使用示范如下表所示：<br>
    <br>
    <table class="tabel">
      <tbody>
        <tr class="d1">
          <td style="width: 400px;" align="center"><b>运算符函数</b></td>
          <td style="width: 200px;" align="center"><span style="font-weight: bold;">举
              例</span></td>
          <td align="center"><b> 描述</b></td>
        </tr>
        <tr>
          <td>bool operator!=(const QMap&lt;Key, T&gt; &amp; other) const</td>
          <td>&nbsp;m1 != m2;</td>
          <td> 两个映射的元素不一样，不等号判断结果为 true。 </td>
        </tr>
        <tr class="d1">
          <td>bool operator==(const QMap&lt;Key, T&gt; &amp; other) const</td>
          <td>&nbsp;m1 == m2;</td>
          <td> 两个映射的元素不一样，等于号判断结果为 false。</td>
        </tr>
        <tr>
          <td>QMap&lt;Key, T&gt; &amp; operator=(const QMap&lt;Key, T&gt; &amp;
            other)</td>
          <td>&nbsp;m1 = m2;</td>
          <td> 将 m2 所有元素复制给 m1，执行后二者相等。 </td>
        </tr>
        <tr class="d1">
          <td>QMap&lt;Key, T&gt; &amp; operator=(QMap&lt;Key, T&gt; &amp;&amp;
            other)</td>
          <td>&nbsp;m1 = std::move(m2);</td>
          <td> 将 m2 中所有元素移动给m1，m2自己清空。 </td>
        </tr>
        <tr>
          <td>T &amp; operator[](const Key &amp; key)</td>
          <td>&nbsp;m2["Cell"]= 18;</td>
          <td style="height: 16px;"> 修改了 "Cell" 对应的value值。 </td>
        </tr>
        <tr class="d1">
          <td>const T operator[](const Key &amp; key) const</td>
          <td style="height: 16px;">&nbsp;qDebug()&lt;&lt; m1["Alice"];</td>
          <td> 打印 "Alice" 对应的常量值。 </td>
        </tr>
      </tbody>
    </table>
    <br>
    （7）迭代器函数<br>
    映射类也定义了 STL 风格和 Qt 命名风格的迭代器：<br>
    <div class="code">class&nbsp;&nbsp; &nbsp;const_iterator&nbsp;&nbsp;
      //STL风格只读迭代器<br>
      class&nbsp;&nbsp; &nbsp;iterator&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;
      &nbsp;&nbsp;&nbsp;&nbsp; //STL风格读写迭代器<br>
      typedef&nbsp;&nbsp;&nbsp; ConstIterator&nbsp; //Qt 风格只读迭代器<br>
      typedef&nbsp;&nbsp;&nbsp;
      Iterator&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; //Qt风格读写迭代器</div>
    STL 风格迭代器使用示范：<br>
    <div class="code">QMap&lt;QString, int&gt;::const_iterator i =
      map.constBegin();<br>
      while (i != map.constEnd()) {<br>
      &nbsp;&nbsp;&nbsp; cout &lt;&lt; i.key() &lt;&lt; ": " &lt;&lt; i.value()
      &lt;&lt; endl;<br>
      &nbsp;&nbsp;&nbsp; ++i;<br>
      }<br>
    </div>
    获取映射的头部元素、尾部假想元素的迭代器函数列举如下：<br>
    <div class="code">iterator&nbsp;&nbsp; &nbsp;begin()&nbsp;&nbsp;&nbsp;&nbsp;
      //指向头部的读写迭代器<br>
      const_iterator&nbsp;&nbsp; &nbsp;begin() const&nbsp;&nbsp;&nbsp;
      &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; //指向头部的只读迭代器<br>
      const_iterator&nbsp;&nbsp; &nbsp;cbegin() const&nbsp;&nbsp;&nbsp;
      &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; //指向头部的只读迭代器<br>
      const_iterator&nbsp;&nbsp;&nbsp; constBegin() const&nbsp;
      //指向头部的只读迭代器，Qt风格<br>
      iterator&nbsp;&nbsp;&nbsp; end()&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      //指向尾部后面假想元素的读写迭代器<br>
      const_iterator&nbsp;&nbsp;&nbsp; end() const&nbsp;&nbsp;&nbsp;
      &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; //指向尾部后面假想元素的只读迭代器<br>
      const_iterator&nbsp;&nbsp; &nbsp;cend() const&nbsp;&nbsp;&nbsp;
      &nbsp;&nbsp;&nbsp; &nbsp;&nbsp; //指向尾部后面假想元素的只读迭代器<br>
      const_iterator&nbsp;&nbsp;&nbsp; constEnd() const&nbsp; &nbsp;
      //指向尾部后面假想元素的只读迭代器，Qt风格</div>
    注意 *end() 返回的迭代器通常只用来做不等于判断，它指向的东西根本不存在， *end() 仅用于越界判断。<br>
    虽然获取头部、尾部迭代器的函数多，其实功能类似，起了一堆名字是方便兼容 STL 风格函数命名。<br>
    查找指定 key 键对应的迭代器位置，使用下面函数：<br>
    <div class="code">iterator&nbsp;&nbsp;&nbsp; find(const Key &amp;
      key)&nbsp;&nbsp;&nbsp; //根据指定key查找所在位置的读写迭代器<br>
      const_iterator&nbsp;&nbsp;&nbsp; find(const Key &amp; key)
      const&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;
      //根据指定key查找所在位置的只读迭代器，STL风格<br>
      const_iterator&nbsp;&nbsp;&nbsp; constFind(const Key &amp; key)
      const&nbsp;&nbsp;&nbsp; //根据指定key查找所在位置的只读迭代器，Qt风格</div>
    如果存在 key 键的一对多映射，返回排在最前面的 key 节点迭代器，相同 key 的多个节点会排在该迭代器之后连续位置；<br>
    如果找不到包含指定 key 的元素，那么查找函数返回 end() 尾部虚假元素迭代器，注意判断几个 *find 函数的返回值。<br>
    根据读写迭代器指定位置，可以删除该位置元素：<br>
    <div class="code">iterator&nbsp;&nbsp;&nbsp; erase(iterator pos)</div>
    删除后返回指向下一元素的迭代器，注意可能是 end() 位置。<br>
    <br>
    QMap 在绝大多数情况下，都是用于一对一映射，但是它也提供了一对多映射的接口函数：<br>
    <div class="code"> //插入指定键值对，如果之前有该键的元素，那么不会替换旧元素，直接增加新的元素，造成一对多映射<br>
      iterator&nbsp;&nbsp;&nbsp; insertMulti(const Key &amp; key, const T &amp;
      value)&nbsp;&nbsp; //插入一对多映射元素<br>
      iterator&nbsp;&nbsp;&nbsp; insertMulti(const_iterator pos, const Key &amp;
      key, const T &amp; value) //在建议的 pos 位置附近插入一对多映射元素</div>
    insertMulti() 会直接向映射添加键值对，并且不会替换旧的相同键值节点，所以会造成多个节点拥有相同的键值，一般不建议这样调用，Qt 专门封装了
    QMultiMap 类用于处理一对多映射。<br>
    <br>
    由于 insertMulti() 会造成一对多映射，红黑树是排序树，同样的 key 键节点是按照排序相邻的，迭代器位置是连续排布的，可以获取一个 key
    对应的多个元素迭代器范围：<br>
    <div class="code">QPair&lt;iterator, iterator&gt;&nbsp;&nbsp;&nbsp;
      equal_range(const Key &amp; key)&nbsp; //返回一对迭代器<br>
      //QPair&lt;iterator, iterator&gt;&nbsp;
      中，第一个迭代器是排在最前面的key键节点位置，第二个是排在最后的key键节点位置<br>
    </div>
    <br>
    根据红黑树的排序特性，QMap 还提供了查找 key 下边界和上边界的迭代器函数：<br>
    <div class="code">iterator&nbsp;&nbsp;&nbsp; lowerBound(const Key &amp;
      key)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; //查找 key 下边界的读写迭代器<br>
      const_iterator&nbsp;&nbsp;&nbsp; lowerBound(const Key &amp; key) const
      //查找 key 下边界的只读迭代器<br>
      iterator&nbsp;&nbsp;&nbsp; upperBound(const Key &amp;
      key)&nbsp;&nbsp;&nbsp; //查找 key 上边界的读写迭代器<br>
      const_iterator&nbsp;&nbsp;&nbsp; upperBound(const Key &amp; key) const
      //查找 key 上边界的只读迭代器 </div>
    key 下边界的意思是按照从小到大顺序，找到红黑树中首个满足如下条件的 keyLB 节点：&nbsp; <br>
    keyLB &gt;= key<br>
    如果映射存在 key 节点，那么返回第一个键值等于 key 的节点迭代器；<br>
    如果没有 key 节点，那么返回首个大于 key 的节点迭代器。举例如下：<br>
    <div class="code">QMap&lt;int, QString&gt; map;<br>
      map.insert(1, "one");<br>
      map.insert(5, "five");<br>
      map.insert(10, "ten");<br>
      <br>
      map.lowerBound(0);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; // returns iterator to
      (1, "one")<br>
      map.lowerBound(1);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; // returns iterator to
      (1, "one")<br>
      map.lowerBound(2);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; // returns iterator to
      (5, "five")<br>
      map.lowerBound(10);&nbsp;&nbsp;&nbsp;&nbsp; // returns iterator to (10,
      "ten")<br>
      map.lowerBound(999);&nbsp;&nbsp;&nbsp; // returns end()</div>
    key 上边界的意思是按照从小到大顺序，找到红黑树中首个满足如下条件的节点 keyUB：<br>
    keyUB &gt; key<br>
    上边界总是返回大于 key 的最邻近节点迭代器。<br>
    举例如下：<br>
    <div class="code">QMap&lt;int, QString&gt; map;<br>
      map.insert(1, "one");<br>
      map.insert(5, "five");<br>
      map.insert(10, "ten");<br>
      <br>
      map.upperBound(0);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; // returns iterator to
      (1, "one")<br>
      map.upperBound(1);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; // returns iterator to
      (5, "five")<br>
      map.upperBound(2);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; // returns iterator to
      (5, "five")<br>
      map.upperBound(10);&nbsp;&nbsp;&nbsp;&nbsp; // returns end()<br>
      map.upperBound(999);&nbsp;&nbsp;&nbsp; // returns end()</div>
    <br>
    （8）容器类型转换函数<br>
    Qt 提供了映射类，STL 也有自己映射类，两种映射类互相转换的函数如下：<br>
    <div class="code">std::map&lt;Key, T&gt;&nbsp;&nbsp; &nbsp;toStdMap()
      const&nbsp; //转为 STL 映射类<br>
      QMap(const std::map&lt;Key, T&gt; &amp; other) //构造函数，根据 STL 映射构造 QMap 映射<br>
    </div>
    QMap 另外支持两个映射合并，将参数 other 映射的元素全部复制添加给自己，如果两个映射都包含相同的 key，那么合并类似
    insertMulti() 造成一对多映射：<br>
    <div class="code">QMap&lt;Key, T&gt; &amp;&nbsp;&nbsp;&nbsp; unite(const
      QMap&lt;Key, T&gt; &amp; other)</div>
    insertMulti() 和 unite() 会无脑添加新元素，即使新的键值对与旧节点完全一样，比如：<br>
    <div class="code">&nbsp;&nbsp;&nbsp; QMap&lt;QString, int&gt; m1;<br>
      &nbsp;&nbsp;&nbsp; m1["Alice"] =&nbsp; 20;<br>
      &nbsp;&nbsp;&nbsp; QMap&lt;QString, int&gt; m2;<br>
      &nbsp;&nbsp;&nbsp; m2["Alice"] =&nbsp; 20;<br>
      <br>
      &nbsp;&nbsp;&nbsp; m1.unite( m2 );<br>
      &nbsp;&nbsp;&nbsp; m1.insertMulti("Alice",20 );<br>
      <br>
      &nbsp;&nbsp;&nbsp; qDebug()&lt;&lt;m1&lt;&lt;endl&lt;&lt;m2;</div>
    打印结果是 m1 包含三个相同节点：<br>
    <div class="output"> QMap(("Alice", 20)("Alice", 20)("Alice", 20)) <br>
      QMap(("Alice", 20))<br>
    </div>
    <br>
    （9）其他内容<br>
    映射类也支持数据串行化，进行数据流输入和输出，但注意前提是 key 和 value 的类型都必须支持串行化：
    <div class="code">QDataStream &amp;&nbsp;&nbsp;
      &nbsp;operator&lt;&lt;(QDataStream &amp; out, const QMap&lt;Key, T&gt;
      &amp; map)&nbsp; //串行化输出<br>
      QDataStream &amp;&nbsp;&nbsp; &nbsp;operator&gt;&gt;(QDataStream &amp; in,
      QMap&lt;Key, T&gt; &amp; map)&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;
      &nbsp;&nbsp;&nbsp; &nbsp;&nbsp; //串行化输入</div>
    <br>
    关于 QMap，这里再提醒两个注意事项：<br>
    <b>① 不能使用 map[key] 这种形式查找映射里是否包含键 key 的元素，因为 operator[](const Key &amp; key)
      函数在找不到 key 元素时，自动调用 value 类默认构造函数为映射添加 key-value 新元素。</b><br>
    应该用 contains(key) 来判断是否包含该 key 元素，或者用&nbsp; map.value( key ) 函数查找值，value()
    函数不会为映射添加新元素，虽然 value() 函数找不到时也会返回 value 类型默认构造的值，但不会改变映射内容。<br>
    <br>
    <b>② 一般不建议使用 QMap 的 insertMulti() 和 unite() 函数进行多重映射添加或映射合并，Qt 单独提供了
      QMultiMap 表示多重映射，在程序中尽量让 QMap 保持一对一映射，避免代码的误解。</b><br>
    <br>
    下面开始本小节的示例程序：<br>
    我们打开 QtCreator，新建一个 Qt Widgets Application 项目，在新建项目的向导里填写：<br>
    ①项目名称 nameage，创建路径 D:\QtProjects\ch09，点击下一步；<br>
    ②套件选择里面选择全部套件，点击下一步；<br>
    ③基类选择 QWidget，点击下一步；<br>
    ④项目管理不修改，点击完成。<br>
    我们打开 widget.ui 界面文件，按照下图拖入控件：<br>
    <center> <img src="images/ch09/ch09-03-01.png" alt="ui" width="800"></center>
    我们首先将窗口宽度设为 480，高度 300，这样能放下四个并排的按钮，然后逐个拖入控件：<br>
    第一行是标签控件，文本为 "姓名-年龄映射" 。<br>
    第二行为列表控件，对象名 listWidget。<br>
    第三行控件为：标签 "姓名"，单行编辑器 lineEditName，标签 "年龄"，旋钮编辑框 spinBoxAge，第三行控件按水平布局器排列。<b>注
      意设置旋钮编辑框的 sizePolicy 属性，将水平策略设置为 Expanding。</b><br>
    第四行为四个按钮："添加元素" 按钮 pushButtonAdd，"删除匹配姓名元素" 按钮 pushButtonDel，"查找匹配姓名元素" 按钮
    pushButtonFindName，"查找匹配年龄元素" 按钮 pushButtonFindAge，四个按钮也使用水平布局排列。<br>
    第五行是丰富文本编辑框，对象名 textEdit，该编辑框默认文本设置为 "结果显示" 。<br>
    窗口整体使用垂直布局，窗口大小 480*300 。<br>
    <br>
    控件布局设置好之后，我们依次右键点击 4 个按钮，在右键菜单选择“转到槽...”，弹出如下对话框：<br>
    <center><img src="images/slots/buttonclicked.png" alt="slot"></center>
    选择信号 clicked() ，点击 OK 按钮，为 4 个按钮都添加对应的槽函数。<br>
    槽函数添加完成后，我们保存界面文件，关闭界面文件，然后对头文件 widget.h 进行编辑：<br>
    <div class="code">
      <style type="text/css">
p, li { white-space: pre-wrap; }
</style> <pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#ifndef</span><span style=" color:#c0c0c0;"> </span>WIDGET_H</pre>
      <pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#define</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">WIDGET_H</span></pre>
      <pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">&lt;QWidget&gt;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">&lt;QMap&gt;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//映射类</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">namespace</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">:</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">public</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QWidget</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000080;">Q_OBJECT</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">public</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">explicit</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QWidget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span>parent<span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">0</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">~</span><span style=" font-style:italic; color:#000000;">Widget</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">slots</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonAdd_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonDel_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonFindName_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonFindAge_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">Ui</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//映射类对象，保存姓名-年龄映射</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QMap</span><span
style=" color:#000000;">&lt;</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#000000;">&gt;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//枚举映射对象的内容，显示到列表控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">showNameAgeMap</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">};</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#endif</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">WIDGET_H</span></pre>
</div>
    在文件开头，我们添加了 QMap 类的头文件包含；<br>Widget 类内部有 4 个槽函数是通过右键菜单添加的；<br>Widget 类末尾添加了映射类对象 m_mapNameAge，key 类型为 QString，value 类型为 int；<br>然后添加了 showNameAgeMap() 函数，专门枚举映射对象的内容，显示到界面的列表控件。<br>
          <br>接下来我们分段编辑源文件 widget.cpp 的内容，首先是构造函数和析构函数部分：<br>
    <div class="code"><span style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"widget.h"</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"ui_widget.h"</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">&lt;QDebug&gt;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">&lt;QMessageBox&gt;</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">Widget</span><span style=" color:#000000;">(</span><span
style=" color:#800080;">QWidget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">*</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QWidget</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setupUi</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//设置年龄范围</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">spinBoxAge</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setRange</span><span
style=" color:#000000;">(</span><span style=" color:#000080;">0</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">600</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//结果显示框设置只读</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setReadOnly</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">true</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//初始化添加几个元素到映射</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"Alice"</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">20</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"Bob"</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">23</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"Cass"</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">23</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"Daff"</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">21</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//显示映射到列表控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">showNameAgeMap</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::~</span><span
style=" font-style:italic; color:#000000;">Widget</span><span style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">delete</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
          文件开头添加了调试信息类和消息框类的头文件包含。<br>构造函数里添加了几行代码，首先将年龄控件 spinBoxAge 的取值范围设置为 0~600 ；<br>设置文本编辑框 textEdit 为只读模式，避免用户修改结果编辑框内容；<br>然后为成员变量&nbsp; m_mapNameAge 添加了四个键值对；<br>构造函数最后调用 showNameAgeMap() 将映射对象的内容显示到列表控件。<br>
          析构函数的代码没有修改，下面我们来编辑 showNameAgeMap() 函数代码：<br>
   <div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">showNameAgeMap</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">listWidget</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">clear</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;">    </span><span
style=" color:#008000;">//清空旧内容</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//获取所有</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">的列表</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QList</span><span
style=" color:#000000;">&lt;</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">&gt;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">listKeys</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_mapNameAge</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">keys</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">listKeys</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">count</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//遍历</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">for</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">int</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">i</span><span style=" color:#000000;">=</span><span style=" color:#000080;">0</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">i</span><span
style=" color:#000000;">&lt;</span><span style=" color:#000000;">nCount</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">i</span><span
style=" color:#000000;">++)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#008000;">//根据</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key-value</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">构造一行字符串</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">curText</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"%1\t%2"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">listKeys</span><span
style=" color:#000000;">[</span><span style=" color:#000000;">i</span><span style=" color:#000000;">]</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">[</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">listKeys</span><span
style=" color:#000000;">[</span><span style=" color:#000000;">i</span><span style=" color:#000000;">]</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">]</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#008000;">//添加到列表控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">listWidget</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">addItem</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">curText</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
          showNameAgeMap() 内部先清空了列表控件内容；<br>获取 m_mapNameAge 映射所有的键列表；<br>所有键的数量也就是映射中元素的个数，将数量保存到 nCount ；<br>然后循环遍历所有的键、值内容，构造文本，添加给 listWidget 。<br>showNameAgeMap() 是通过获取所有键列表的方式遍历映射对象，也可以直接用迭代器方式遍历，在上面迭代器函数介绍部分有示范代码。<br>
          <br>接下来逐个编辑按钮槽函数的代码，首先是“添加”按钮的槽函数：<br>
          <div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonAdd_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//检查姓名</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">，不能为空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditName</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"检查姓名key"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"姓名为空，不能添加。"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//添加姓名-年龄对</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">[</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">]</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">spinBoxAge</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">showNameAgeMap</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"已添加姓名-年龄新元素。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
          
          该槽函数首先获取姓名编辑框的字符串，存到 strName ，并判断字符串是否为空，空字符串不处理直接返回；<br>对于非空字符串，继续后面代码；<br>使用中括号的方式，为映射 m_mapNameAge 添加键值对；<br>然后调用&nbsp; showNameAgeMap() 显示添加新元素后的映射到列表控件；<br>最后在结果显示编辑框里，显示已添加新元素的信息。<br>
          <br>“删除匹配姓名元素”按钮槽函数代码如下：<br>
    <div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonDel_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//检查姓名</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">，不能为空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditName</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"检查姓名key"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"姓名为空，不能删除。"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//查找是否存在该</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">contains</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"指定姓名不存在，无法删除。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//删除匹配</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">的元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">remove</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">showNameAgeMap</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"指定姓名元素已经删除。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
          
          该槽函数开头类似的获取姓名编辑框的文本，并判断是否为空，空字符串不处理，对于非空字符串才进行后续处理；<br>调用 m_mapNameAge.contains() 函数判断映射里是否存在键 strName&nbsp; ，如果不存在就不处理；<br>如果存在键 strName&nbsp; ，那么调用&nbsp;&nbsp; m_mapNameAge.remove() 删除匹配的元素；<br>最后更新列表控件的显示，并将已经删除元素的信息到结果编辑框。<br><br>添加和删除操作修改了映射&nbsp; m_mapNameAge 的内容，因此需要调用&nbsp; showNameAgeMap() 更新列表控件的显示，后面的查询按钮操作没有修改映射内容，就不需要更新列表控件。<br>
          <br>“查找匹配姓名元素”按钮的槽函数代码如下：<br>
          <div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonFindName_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//检查姓名</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">，不能为空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditName</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"检查姓名key"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"姓名为空，不能查找。"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//查找是否存在该</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">contains</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"指定姓名不存在。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//找到了，这里是一对一映射，一个</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">只有一个</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">value</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"已找到指定姓名为</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">%1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">的元素，年龄为</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">%2"</span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">            </span><span style=" color:#000000;">.</span><span
style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">[</span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">]</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
          该槽函数类似地先获取姓名字符串，并判断是否为空，空字符串不处理，非空字符串才进行后面处理；<br>调用&nbsp; m_mapNameAge.contains() 判断映射是否包含键 strName ，<br>如果不包含键就显示 "指定姓名不存在。" 的信息到结果编辑框；<br>如果包含，就显示已找到的信息到结果编辑框。<br>本示例是一对一的映射，映射中所有 key 都是唯一的，所以一个 key 只有一个 value，不需要考虑多重映射。<br>
          <br>最后是“查找匹配年龄元素”按钮的槽函数代码：<br>
          <div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonFindAge_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//获取年龄</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nAge</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">spinBoxAge</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//根据年龄反查姓名，可能存在多个同龄人</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QList</span><span
style=" color:#000000;">&lt;</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">&gt;</span><span style=" color:#c0c0c0;">  </span><span
style=" color:#000000;">listNames</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_mapNameAge</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">keys</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nAge</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//检查是否找到了</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strResult</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">listNames</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">count</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">&lt;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">1</span><span style=" color:#c0c0c0;">  </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"没有匹配该年龄的元素。"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">else</span><span
style=" color:#008000;">//存在指定年龄的元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"找到了匹配年龄的元素</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">%1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">个，列举如下：\r\n"</span><span style=" color:#000000;">).</span><span
style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">nCount</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">for</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">int</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">i</span><span style=" color:#000000;">=</span><span style=" color:#000080;">0</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">i</span><span
style=" color:#000000;">&lt;</span><span style=" color:#000000;">nCount</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">i</span><span
style=" color:#000000;">++)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">            </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"%1\t%2\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#000000;">listNames</span><span style=" color:#000000;">[</span><span
style=" color:#000000;">i</span><span style=" color:#000000;">]).</span><span style=" color:#000000;">arg</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">nAge</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//显示结果</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
          这是个反查函数，根据 value 反查有几个 key。一对一映射的 key 唯一，但是多个 key 可以有相同的 value 值，比如多个人姓名不同，年龄相同。<br>该函数先获取年龄旋钮框的数值 nAge；<br>调用 m_mapNameAge.keys( nAge ) 根据年龄反查匹配的所有 key 列表；<br>然后获取反查的 key 列表中计数 nCount；<br>如果计数 nCount 小于 1，说明没有找到，设置结果字符串为 "没有匹配该年龄的元素。"；<br>否则有匹配的元素，那么通过循环遍历所有匹配的键值对，构造结果字符串；<br>最后显示结果字符串到结果编辑框。<br>
          示例代码就是上面内容，我们保存代码文件，构建并运行示例：<br>
    <center><img src="images/ch09/ch09-03-02.png" alt="run1"></center>

          我们在窗口构造函数添加的四个映射元素显示在了列表控件里。<br>
          我们设置年龄为 23 ，然后点击“查找匹配年龄元素”按钮，可以看到反查结果：<br>
    <center><img src="images/ch09/ch09-03-03.png" alt="run2"></center>
          其他功能读者都可以自行测试一下，注意示例中映射的 key 是区分字母大小写的，大写字母的键排在前面，小写字母的键排在后面。本小节的内容到这，我们下面小节介绍多映射 QMultiMap 的内容。<br><br>
    <div class="os2">9.3.2 多映射 QMultiMap</div>
    <br>
    QMultiMap 是 QMap 的派生类，继承了 QMap 绝大多数的功能函数，同时也根据一对多映射的特性做了改进，将基类的部分函数功能进行了重载，使用 QMultiMap&nbsp; 时需要注意与基类的区别。除了基类的功能函数，QMultiMap 类的函数主要有如下几个：<br>
          （1）构造函数<br>
          <div class="code">QMultiMap() //默认构造函数 <br>QMultiMap(std::initializer_list&lt;std::pair&lt;Key, T&gt; &gt; list) //初始化列表构造函数<br>QMultiMap(const QMap&lt;Key, T&gt; &amp; other) //复制构造函数，支持从 QMap 和 QMultiMap 构造新对象</div>第一个是不带参数的默认构造函数；第二个是支持 C++11 特性的初始化列表构造函数；<br>第三个是复制构造函数，参数里无论是 QMap 对象或 QMultiMap 对象都可以进行复制构造。<br>QMultiMap 也是支持移动构造函数的，从基类自动继承，比如下面代码：<br>
          <div class="code">&nbsp;&nbsp;&nbsp; QMultiMap&lt;QString, QString&gt; namePhone{<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {"Alice", "10086"},<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {"Alice", "10087"},<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {"Bob", "10010"},<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {"Bob", "10011"}<br>&nbsp;&nbsp;&nbsp; }; <br>&nbsp;&nbsp;&nbsp; qDebug()&lt;&lt;namePhone;<br>&nbsp;&nbsp;&nbsp; QMultiMap&lt;QString, QString&gt; namePhone2( namePhone );<br>&nbsp;&nbsp;&nbsp; qDebug()&lt;&lt;namePhone2;<br><br>&nbsp;&nbsp;&nbsp; QMultiMap&lt;QString, QString&gt; namePhone3 =&nbsp; std::move(namePhone);<br>&nbsp;&nbsp;&nbsp; qDebug()&lt;&lt;namePhone&lt;&lt;endl&lt;&lt;namePhone3;</div>
          示例代码中三个对象依次使用初始化列表构造、复制构造和移动构造，打印结果如下：<br>
          <div class="output">QMap(("Alice", "10087")("Alice", "10086")("Bob", "10011")("Bob", "10010"))<br>QMap(("Alice", "10087")("Alice", "10086")("Bob", "10011")("Bob", "10010"))<br>QMap() <br>QMap(("Alice", "10087")("Alice", "10086")("Bob", "10011")("Bob", "10010"))</div>
          QMultiMap 的打印函数自动使用了基类的版本，所以看到类名是 QMap，其实是 QMultiMap&nbsp; 对象。<br><br>
          （2）添加函数<br>
            <div class="code">QMap&lt;Key, T&gt;::iterator QMultiMap::​insert(const Key &amp; key, const T &amp; value)<br>QMap&lt;Key, T&gt;::iterator QMultiMap::​insert(QMap&lt;Key, T&gt;::const_iterator pos, const Key &amp; key, const T &amp; value)</div>QMultiMap 的迭代器完全从基类 QMap 继承，因此可以看到参数和返回值的迭代器都是 QMap 的迭代器。但要注意 QMultiMap::​insert() 总是插入新的 key-value 节点，不会对旧节点进行替换，即使新旧节点键值一模一样，也会增加新的节点。<br>第一个 ​insert() 自动添加新节点到红黑树的排序位置，红黑树只按照 key 排序，同样 key 的多个 value 值不会排序，同样 key 的新节点总是插入到同样 key 旧节点的最前面。<br>第二个 insert() 会在建议的迭代器位置 pos 附近插入新节点，但不一定是指定位置，最终还是要按红黑树的 key 进行排序确定位置。<br>
          （3）删除函数<br>
            <div class="code">int&nbsp;&nbsp;&nbsp; remove(const Key &amp; key, const T &amp; value)<br>int&nbsp;&nbsp;&nbsp; remove(const Key &amp; key)</div>第一个删除函数会删除所有键为 key、值为 value 的节点，返回值是删除的个数，因为多映射对象中可以插入多个相同键且相同值的节点，所以第一个删除函数返回值可能大于 1 。 <br>第二个删除函数会删除所有键为 key 的节点，返回值是删除的个数。两个删除函数在找不到匹配节点时，不删除任何东西，返回值是 0 。<br>
          （4）访问和查询函数<br>统计多映射对象所有节点个数使用下面函数：<br>
            <div class="code">int count() const</div>
          统计所有键为 key 且值为 value 的节点数使用下面函数：<br>
            <div class="code">int count(const Key &amp; key, const T &amp; value) const</div>
          
          统计所有键为 key 的节点数，使用下面函数：<br>
            <div class="code">int count(const Key &amp; key) const</div>
          判断多映射对象是否包含 key-value 对的函数如下：<br>
            <div class="code">bool contains(const Key &amp; key, const T &amp; value) const</div>
          判断多映射对象是否包含 key 的函数如下：<br>
           <div class="code">bool contains(const Key &amp; key) const</div>
          <br>根据 key-value 对查找匹配节点的迭代器位置函数如下：<br>
           <div class="code">QMap&lt;Key, T&gt;::const_iterator&nbsp;&nbsp; &nbsp;constFind(const Key &amp; key, const T &amp; value) const //只读迭代器查询，Qt风格函数名<br>QMap&lt;Key, T&gt;::const_iterator&nbsp;&nbsp;&nbsp; find(const Key &amp; key, const T &amp; value) const&nbsp; //只读迭代器，STL风格函数名<br>QMap&lt;Key, T&gt;::iterator&nbsp;&nbsp;&nbsp; find(const Key &amp; key, const T &amp; value)&nbsp; //读写迭代器查询</div>
          根据 key 查找匹配节点的迭代器位置函数如下：<br>
           <div class="code">QMap&lt;Key, T&gt;::const_iterator&nbsp;&nbsp; &nbsp;constFind(const Key &amp; key) const&nbsp; //只读迭代器查询，Qt风格函数名<br>QMap&lt;Key, T&gt;::const_iterator&nbsp;&nbsp;&nbsp; find(const Key &amp; key) const&nbsp; //只读迭代器，STL风格函数名<br>QMap&lt;Key, T&gt;::iterator&nbsp;&nbsp;&nbsp; find(const Key &amp; key)&nbsp; //读写迭代器查询</div>
          <br>
          （5）替换和交换函数<br>多映射的节点替换函数如下：<br>
            <div class="code">QMap&lt;Key, T&gt;::iterator QMultiMap::​replace(const Key &amp; key, const T &amp; value)</div>
          节点替换函数在查找到匹配 key 的一个或多个节点时，替换之前最后一次插入的匹配 key 节点；<br>如果找不到匹配 key 的节点，那么会新增一个 key-value 节点。<br>多映射与其他同类对象的交换函数如下：<br>
            <div class="code">void QMultiMap::​swap(QMultiMap&lt;Key, T&gt; &amp; other)</div>
          swap() 函数不会失败，并且效率非常高。<br><br>
          （6）运算符函数<br>QMultiMap 新加了 + 和 += 运算符函数，用于合并对象：<br>
            <div class="code">QMultiMap QMultiMap::​operator+(const QMultiMap &amp; other) const<br>QMultiMap &amp; QMultiMap::​operator+=(const QMultiMap &amp; other)</div>合并后的对象节点数总是等于合并前两个对象节点数之和， 两个对象同样 key-value 的节点不会替换，节点数量直接重复累加。<br>另外 QMultiMap 取消了 operator[] 运算符函数，由于多映射的 key 很可能对应多个 value，同样 key 的多个节点定位不明确，所以不能用 operator[] 运算符函数。替换之前最新插入的键为 key 的节点使用 replace() 函数。<br>
          <br>QMap 和 QMultiMap 二者功能函数的主要区别对比如下表所示：<br>
           <br>
    <table class="tabel">
      <tbody>
        <tr class="d1">
          <td style="width:20%;" align="center"><b>功能</b></td>
          <td style="width: 40%;" align="center"><b>QMap 函数</b></td>
          <td align="center"><b> QMultiMap 函数</b></td>
        </tr>
        <tr>
          <td>一对一添加节点</td>
          <td style="height: 32px;"><b>insert(key,value)：无匹配key时直接插入新节点，有匹配key时替换旧节点。</b></td>
          <td> replace(key,value)：无匹配key时直接插入新节点，有匹配key时，替换之前最新插入的同样key节点。 </td>
        </tr>
        <tr class="d1">
          <td>一对多添加节点</td>
          <td> insertMulti(key,value)：直接将新节点插入到红黑树，不考虑之前有无同样键值的节点。</td>
          <td> <b>insert(key,value)：直接将新节点插入到红黑树，不考虑之前有无同样键值的节点。<br></b>insertMulti(key,value)函数同基类。<b><br></b> </td>
        </tr>
        <tr>
          <td>中括号运算符</td>
          <td> operator[](key)：根据key读写匹配的节点，如果没有匹配的，自动添加该 key 节点。</td>
          <td> 没有中括号运算符，对于类似功能，读操作调用 value(key)函数，写操作调用replace(key,value)。 </td>
        </tr>
        <tr class="d1">
          <td>合并两个对象</td>
          <td> 无 + 和 += 运算符函数。QMap::​unite(other)可以将参数other所有节点添加给自己，类似 += 功能。</td>
          <td style="height: 16px;">通过  + 和 += 运算符函数。</td>
        </tr>
        <tr>
          <td>查询函数</td>
          <td>count(key)、contains(key)、find(key)、constFind(key)，只需要通过 key 查询节点，因为通常是一对一映射。</td>
          <td> 不仅有 count(key)、contains(key)、find(key)、constFind(key)，一对多映射查询时还可以根据键值对进行查询<br>count(key,value)、contains(key,value)、find(key,value)、constFind(key,value)。 </td>
        </tr>
        <tr class="d1">
          <td>删除函数</td>
          <td style="height: 16px;"> remove(key)，删除匹配 key 的节点。 </td>
          <td> 两个删除函数，remove(key)删除匹配 key 的所有节点，remove(key,value)删除匹配 key-value 的所有节点。 </td>
        </tr>
      
      </tbody>
    </table>
    <br><b>需要特别注意的就是 insert() 函数，基类 QMap 和 派生类 QMultiMap 的 insert() 函数名一样，功能却不一样，基类 QMap 是一对一添加或替换，而派生类 QMultiMap 是一对多的重复添加。</b><br><br>QMultiMap 的功能函数介绍到这，我们下面学习一个电话号码本的示例，将姓名映射到多个电话号码。<br>我们打开 QtCreator，新建一个 Qt Widgets Application 项目，在新建项目的向导里填写：<br>①项目名称 namephone，创建路径 D:\QtProjects\ch09，点击下一步；<br>②套件选择里面选择全部套件，点击下一步；<br>③基类选择 QWidget，点击下一步；<br>④项目管理不修改，点击完成。<br>
          我们打开 widget.ui 界面文件，按照下图拖入控件：<br>
     <center> <img src="images/ch09/ch09-03-04.png" alt="ui" width="800"></center>
          第一行是标签控件，文本为“姓名-电话映射”。<br>第二行是列表控件，对象名为 listWidget。<br>第三行是标签“姓名”，单行编辑器 lineEditName，标签“电话”，单行编辑器 lineEditPhone，第三行按水平布局器排布。<br>第四行和第五行是 6 个按钮，依次为 “添加元素”按钮 pushButtonAdd、“替换元素”按钮 pushButtonReplace、“删除匹配姓名”按钮 pushButtonDelName、“删除匹配姓名电话”按钮 pushButtonDelNamePhone，“查询姓名”按钮 pushButtonFindName、“查询电话”按钮 pushButtonFindPhone，第四行和第五行使用一个网格布局器排布。<br>第六行是文本编辑框 textEdit 。<br>窗口整体布局使用垂直布局器，窗口大小 400*400 。<br><br>
          控件布局设置好之后，我们依次右键点击 6 个按钮，在右键菜单选择“转到槽...”，弹出如下对话框：<br>
          <center><img src="images/slots/buttonclicked.png" alt="slot"></center>
          选择信号 clicked() ，点击 OK 按钮，为 6 个按钮都添加对应的槽函数。<br>
          槽函数添加完成后，我们保存界面文件，关闭界面文件，然后对头文件 widget.h 进行编辑：<br>
   <div class="code"><span style=" color:#000080;">#ifndef</span><span style=" color:#c0c0c0;"> </span>WIDGET_H
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#define</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">WIDGET_H</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">&lt;QWidget&gt;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">&lt;QMultiMap&gt;//多重映射模板类</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">namespace</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">:</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">public</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QWidget</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000080;">Q_OBJECT</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">public</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">explicit</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QWidget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span>parent<span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">0</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">~</span><span style=" font-style:italic; color:#000000;">Widget</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">slots</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonAdd_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonReplace_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonDelName_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonDelNamePhone_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonFindName_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonFindPhone_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">Ui</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//多重映射对象，保存姓名电话映射</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QMultiMap</span><span
style=" color:#000000;">&lt;</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">&gt;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_mmapNamePhone</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//枚举映射对象内容，显示到列表控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">showNamePhoneMap</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">};</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#endif</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">WIDGET_H</span></pre></div>
          
          widget.h 文件中，开头添加了多重映射模板类的头文本包含；<br>Widget 类声明中，6 个槽函数是通过右键菜单添加的；<br>声明末尾手动添加了多重映射对象 m_mmapNamePhone，保存姓名到电话的映射关系；<br>手动添加了函数 showNamePhoneMap()，将姓名电话映射的内容显示到窗口的列表控件。<br><br>
          接下来我们分段编辑 widget.cpp 源文件内容，添加功能代码，首先是构造函数、析构函数部分：<br>
 <div class="code"><span style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"widget.h"</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"ui_widget.h"</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">&lt;QDebug&gt;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">&lt;QMessageBox&gt;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">&lt;QRegExp&gt;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//正则表达式</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">&lt;QRegExpValidator&gt;//正则表达式验证器</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">Widget</span><span style=" color:#000000;">(</span><span
style=" color:#800080;">QWidget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">*</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QWidget</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setupUi</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//设置电话号码的限定，这里用正则表达式粗略限定</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">3</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">~</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">14</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">位数字</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QRegExp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">re</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"[0-9]{3,14}"</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QValidator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#000000;">vali</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QRegExpValidator</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">re</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">lineEditPhone</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setValidator</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">vali</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//结果显示框设为只读</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setReadOnly</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">true</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//添加几个多重映射元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mmapNamePhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"Alice"</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"10086"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mmapNamePhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"Alice"</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"10086"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mmapNamePhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"Bob"</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"10010"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mmapNamePhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"Bob"</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"10011"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mmapNamePhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"Ceil"</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"12345"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//显示多重映射到列表控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">showNamePhoneMap</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::~</span><span
style=" font-style:italic; color:#000000;">Widget</span><span style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">delete</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
          
          widget.cpp 开头添加了调试类、消息框、正则表达式和正则表达式验证器等头文件包含，正则表达式用于检查电话号码格式。<br>在构造函数中，定义了一个简单的正则表达式 re，限定 3~14 位的电话号码，实际中的电话号码更复杂，这里使用简单的版本；然后新建了正则表达式验证器 vali，设置给电话号码的编辑框 ui-&gt;lineEditPhone；<br>设置结果显示框 ui-&gt;textEdit 为只读模式；<br>为多重映射对象添加了五个元素，注意键 "Alice" 和 值 "10086" 添加了两次，会生成两个元素，而不会覆盖。<br>构造函数最后调用 showNamePhoneMap() 显示映射的内容到列表控件。<br>析构函数没有修改，使用默认代码。<br><br>
          接下来手动添加 showNamePhoneMap() 函数实体代码：<br>
          <div class="code"><span style=" color:#008000;">//显示多重映射到列表控件</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">showNamePhoneMap</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//清空旧的内容</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">listWidget</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">clear</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//使用迭代器遍历</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QMultiMap</span><span
style=" color:#000000;">&lt;</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">&gt;::</span><span style=" color:#800080;">iterator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_mmapNamePhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">begin</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//循环遍历直到结束</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">while</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_mmapNamePhone</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">end</span><span style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#008000;">//读取键、值，拼接为字符串</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">curText</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"%1\t%2"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">key</span><span style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">value</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#008000;">//添加到列表控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">listWidget</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">addItem</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">curText</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#008000;">//递增迭代器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">++;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
          
          该函数先清空列表控件的旧内容；<br>定义迭代器 it，初始为&nbsp; m_mmapNamePhone 映射对象的开始位置；<br>然后循环遍历映射对象，根据键 it.key() 和值 it.value() 构造字符串，添加给列表控件，<br>循环末尾使用 it++ 递增迭代器位置，进行下一个元素的访问。<br>当 it 等于 m_mmapNamePhone.end() 时，说明遍历结束。<br><br>注意迭代器遍历时，要使用 it++ 或 ++it 移动到下一个元素，不移动位置会导致死循环；<br>另外 m_mmapNamePhone.end() 指向末尾假想元素位置，就是没有指向任何元素，不能访问该迭代器的键或值。<br><br>
          接下来依次编辑各个功能按钮的槽函数代码，首先是“添加元素”按钮的槽函数代码：<br>
   <div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonAdd_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//获取姓名、电话</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditName</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditPhone</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//两个字符串不能为空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">||</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"检查姓名和电话"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"姓名和电话都不能为空！"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//多重映射的添加</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mmapNamePhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">showNamePhoneMap</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"已添加姓名-电话新元素。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
   该函数先获取姓名编辑框、电话编辑框的文本，然后判断两个文本 strName、strPhone 是否为空：<br>如果为空就显示消息框，提示两个文本都不能为空，然后返回；<br>如果非空就继续后面代码，调用 m_mmapNamePhone.insert(strName, strPhone) 为映射添加新元素；<br>然后调用 showNamePhoneMap() 更新列表控件的显示，并将结果编辑框的文本更新。<br>多重映射的 insert() 函数一定会为映射添加新的元素，而不会覆盖同 key 同 value 的旧元素。<br><br>
    “替换元素”按钮的槽函数代码如下：<br>
   <div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonReplace_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//获取姓名、电话</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditName</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditPhone</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//两个字符串不能为空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">||</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"检查姓名和电话"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"姓名和电话都不能为空！"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//多重映射的替换操作，如果没有旧key，会新增元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_mmapNamePhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">replace</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">showNamePhoneMap</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"已完成姓名-电话元素替换。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
   “替换按钮”的槽函数代码非常类似“添加元素”按钮的槽函数代码，只是将多重映射的 insert() 函数换成了 replace() 函数。多重映射的  replace() 函数在能找到 同 key 元素的情况下，替换之前最近插入的同 key 元素，这时候多重映射元素的数量不会增加；如果找不到同 key 元素，那么自动添加新元素，这时候多重映射的元素数量增加一个。<br><br>
   “删除匹配姓名”按钮的槽函数代码如下：<br>
   <div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonDelName_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//获取姓名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditName</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//字符串不能为空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"检查姓名"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"姓名不能为空！"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//可以直接调用删除函数，返回值是删除数量</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nRet</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_mmapNamePhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">remove</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nRet</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">&lt;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">1</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#008000;">//没有删除东西，不需要更新列表控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"指定姓名不存在，无法删除。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#008000;">//更新列表控件、结果显示框</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">showNamePhoneMap</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"已删除匹配姓名元素</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">%1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">个。"</span><span style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">nRet</span><span style=" color:#000000;">)</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
   该函数先获取姓名编辑框的文本，并判断 strName 是否为空，如果为空就显示消息框，然后返回；<br>如果姓名文件非空，那么继续后面代码。<br>QMap 和 QMultiMap 的 remove()&nbsp; 函数都可以直接调用，不需要判断是否包含 key ， remove()&nbsp; 函数返回值是删除元素的数量，如果为 0 说明没有匹配的元素，如果是 1 个或以上，说明删除了返回值数量的匹配元素。<br>上面槽函数在调用 m_mmapNamePhone.remove( strName ) 之后，判断返回值：<br>如果小于 1，说明没有匹配元素，映射对象没有变化，直接显示结果文本，而不需要更新列表控件；<br>如果大于等于 1，说明删除了匹配的元素，调用 showNamePhoneMap() 更新列表控件显示，然后在结果框显示删除元素的个数。<br><br>
   “删除匹配姓名电话”按钮的槽函数代码如下：<br>
    <div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonDelNamePhone_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//获取姓名、电话</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditName</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditPhone</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//两个字符串不能为空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">||</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"检查姓名和电话"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"姓名和电话都不能为空！"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//可以直接调用删除函数，返回值是删除数量</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nRet</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_mmapNamePhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">remove</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nRet</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">&lt;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">1</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#008000;">//没有删除东西，不需要更新列表控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"指定姓名电话元素不存在，无法删除。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#008000;">//更新列表控件，结果显示框</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">showNamePhoneMap</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"已删除匹配姓名电话元素</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">%1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">个。"</span><span style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">nRet</span><span style=" color:#000000;">)</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
   该函数先获取姓名、电话编辑框的文本，并判断是否为空，如果为空就显示消息框后返回；<br>如果 strName 和 strPhone 都非空，继续后面代码。<br>调用 m_mmapNamePhone.remove( strName, strPhone ) 删除同时匹配姓名和电话的元素，返回值是删除的数量。<br>判断返回值 nRet，如果小于 1，说明没有删除元素，直接显示结果框的文本；<br>如果大于等于 1，那么调用 showNamePhoneMap() 更新列表控件显示，并显示删除数量到结果框。<br><br>基类 QMap 只提供了一个 remove( key ) 删除函数，而派生类 QMultiMap 提供了两个删除函数：<br>remove( key ) 和 remove( key, value )，双参数版本的删除函数用于在同时匹配 key 和 value 的情况下删除元素。<br>QMultiMap 的 find() 、count()、 contains() 类似的都有单参数版本和双参数版本，单参数版本函数仅匹配 key，而双参数版本同时匹配 key&nbsp; 和 value。基类 QMap 通常用于一对一映射，一个 key 绑定一个 value，所以不需要双参数的版本。<br><br>
   “查询姓名”按钮的槽函数代码如下：<br>
   <div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonFindName_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//获取姓名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditName</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//姓名不能为空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"检查姓名"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"姓名不能为空！"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//查找姓名对应的电话列表，如果电话列表为空说明没有匹配的key</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QList</span><span
style=" color:#000000;">&lt;</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">&gt;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">listPhones</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_mmapNamePhone</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">values</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strResult</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//结果字符串</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nPhonesCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">listPhones</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">count</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//检查数量</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nPhonesCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">&lt;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">1</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">         </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"没有找到指定姓名元素。"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"已找到匹配姓名元素</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">%1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">个：\r\n"</span><span style=" color:#000000;">).</span><span
style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">nPhonesCount</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">for</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">int</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">i</span><span style=" color:#000000;">=</span><span style=" color:#000080;">0</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">i</span><span
style=" color:#000000;">&lt;</span><span style=" color:#000000;">nPhonesCount</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">i</span><span
style=" color:#000000;">++)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">            </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"%1\t%2\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">listPhones</span><span
style=" color:#000000;">[</span><span style=" color:#000000;">i</span><span style=" color:#000000;">]</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//显示结果字符串</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strResult</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
   该函数先获取姓名字符串的文本，检查是否为空，如果为空就显示消息框后返回；<br>如果非空，那么继续后面代码。<br>调用 m_mmapNamePhone.values( strName ) 查询匹配键 strName 的所有值列表；<br>定义结果字符串 strResult；<br>获取列表 listPhones 的元素计数 nPhonesCount ；<br>判断计数 nPhonesCount ，如果小于 1 ，说明没有映射中没有匹配的键，设置相应 strResult 内容；<br>如果大于等于 1，那么先为 strResult 设置第一行文本，说明匹配个数，<br>然后循环遍历 listPhones 的值列表，将映射中匹配的键值元素逐行添加到 strResult 。<br>最后显示结果字符串到文本框 ui-&gt;textEdit 。<br><br>QMultiMap 的 values() 函数是从基类 QMap 继承的，由于 QMap 通常是一对一映射，所以 QMap 有 values() 函数也很少用。这个 values() 函数其实是为多重映射定制的，更多地用于 QMultiMap 查询匹配 key 的所有 value 列表。如果返回列表的元素计数为 0，那么说明没有找到匹配 key 的元素，如果列表存在 1 个或以上元素，说明找到了所有匹配元素的 value 。<br><br>
   “查询电话”按钮的槽函数代码如下：<br>
   <div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonFindPhone_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//获取电话</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#800000;">lineEditPhone</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//电话不能为空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"检查电话"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"电话不能为空！"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//反向查找，根据value反查key，姓名电话可能重复多个</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QList</span><span
style=" color:#000000;">&lt;</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">&gt;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">listNames</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_mmapNamePhone</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">keys</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strPhone</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strResult</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//结果字符串</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nNamesCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">listNames</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">count</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//检查数量</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nNamesCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">&lt;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">1</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"没有找到匹配电话的元素。"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"已找到匹配电话的元素</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">%1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">个：\r\n"</span><span style=" color:#000000;">).</span><span
style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">nNamesCount</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#808000;">for</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">int</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">i</span><span style=" color:#000000;">=</span><span style=" color:#000080;">0</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">i</span><span
style=" color:#000000;">&lt;</span><span style=" color:#000000;">nNamesCount</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">i</span><span
style=" color:#000000;">++)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">            </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"%1\t%2\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">listNames</span><span
style=" color:#000000;">[</span><span style=" color:#000000;">i</span><span style=" color:#000000;">]</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPhone</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">        </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//显示结果</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;">    </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">textEdit</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strResult</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
   该函数先获取电话编辑框的文本，判断是否为空，如果为空，显示消息框，然后返回；<br>如果文本 strPhone 非空，继续后面代码。<br>调用 m_mmapNamePhone.keys( strPhone ) ，根据值 strPhone 反向查找匹配的 key 列表，同样的电话可能匹配多个姓名，比如公司的公用电话。keys() 函数返回匹配该值的所有键列表。<br>然后定义结果字符串 strResult；<br>获取键列表的计数保存到 nNamesCount；<br>然后对计数 nNamesCount 进行判断，如果小于 1，那么说明没有找到匹配的元素，设置相应的结果字符串；<br>如果大于等于 1，那么先设置 strResult 的第一行文本，说明匹配电话元素的计数，<br>然后循环遍历 listNames 列表，将列表的姓名和查询的电话字符串拼接成一行，添加给 strResult 。<br>最后将 strResult 显示到结果编辑框 ui-&gt;textEdit 里面。<br>
          <br>这个示例的代码介绍到这，我们编译运行该示例：<br>
   <center><img src="images/ch09/ch09-03-05.png" alt="run1"></center>
          
          
          注意看五个元素的位置，多重映射对于 key，这里是 QString 类型的，按照字母顺序排列，区分大小写；<br>而同 key 的多个 value 排列只和添加顺序有关，不考虑值大小或字母序。<br>对于同 key 的多个 value，是按照添加顺序反向排列的，早添加的排在后面，晚添加的排在前面。<br>读者可以查看 Bob 的两个元素，与代码添加顺序是反的。<br>
          我们在姓名编辑框输入 abe，电话编辑框输入 10010，点击“添加元素”按钮：<br>
   <center><img src="images/ch09/ch09-03-06.png" alt="run2"></center>
          abe 因为是小写的，会排在大写字母姓名的末尾。<br>
          我们再把电话编辑框内容改为 56789，点击“删除匹配姓名电话”，可以看到下图结果：<br>
    <center><img src="images/ch09/ch09-03-07.png" alt="run3"></center>
                “删除匹配姓名电话”按钮会同时检查姓名和电话，映射中元素的 key-value&nbsp;必须和编辑框里姓名电话一样才能匹配上，然后才能进行删除。当电话或者姓名有一个不匹配，都不会删除元素，所以上面操作没有找到匹配的元素，无法删除。其他按钮功能读者自行测试。<br>
          本节的内容就到这，下一节我们介绍关于哈希映射的内容。
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