253 lines
23 KiB
HTML
253 lines
23 KiB
HTML
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<title>std::set<Key,Compare,Allocator>::insert</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_container_set_insert skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::set<Key,Compare,Allocator>::</span>insert</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-container.html">container</a>‎ | <a href="cpp-container-set.html">set</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-pair.html"><span class="kw1096">std::<span class="me2">pair</span></span></a><span class="sy1"><</span>iterator,<span class="kw4">bool</span><span class="sy1">></span> insert<span class="br0">(</span> <span class="kw4">const</span> value_type<span class="sy3">&</span> value <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(1)</td>
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<div><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-pair.html"><span class="kw1096">std::<span class="me2">pair</span></span></a><span class="sy1"><</span>iterator,<span class="kw4">bool</span><span class="sy1">></span> insert<span class="br0">(</span> value_type<span class="sy3">&&</span> value <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<td rowspan="142">(3)</td>
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<div><span class="mw-geshi cpp source-cpp">iterator insert<span class="br0">(</span> iterator hint, <span class="kw4">const</span> value_type<span class="sy3">&</span> value <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 前)</span></td>
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<div><span class="mw-geshi cpp source-cpp">iterator insert<span class="br0">(</span> const_iterator hint, <span class="kw4">const</span> value_type<span class="sy3">&</span> value <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp">iterator insert<span class="br0">(</span> const_iterator hint, value_type<span class="sy3">&&</span> value <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(4)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> InputIt <span class="sy1">></span><br />
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<span class="kw4">void</span> insert<span class="br0">(</span> InputIt first, InputIt last <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(5)</td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> insert<span class="br0">(</span> <a href="cpp-utility-initializer_list.html"><span class="kw960">std::<span class="me2">initializer_list</span></span></a><span class="sy1"><</span>value_type<span class="sy1">></span> ilist <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(6)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp">insert_return_type insert<span class="br0">(</span>node_type<span class="sy3">&&</span> nh<span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(7)</td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp">iterator insert<span class="br0">(</span>const_iterator hint, node_type<span class="sy3">&&</span> nh<span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(8)</td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<p>插入元素到容器，若容器未含拥有等价关键的元素。</p>
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<div class="t-li1"><span class="t-li">1-2)</span> 插入 <code>value</code> 。</div>
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<div class="t-li1"><span class="t-li">3-4)</span> 插入 <code>value</code> 到<span class="t-rev-inl t-until-cxx11"><span>尽可能接近</span> <span><span class="t-mark-rev t-until-cxx11">(C++11 前)</span></span></span><span class="t-rev-inl t-since-cxx11"><span>正好前于</span> <span><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></span></span> <code>hint</code> 的位置。</div>
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<div class="t-li1"><span class="t-li">5)</span> 插入来自范围 <code>[first, last)</code> 的元素。 若范围中的多个元素拥有比较等价的关键，则插入哪个元素是未指定的（待决的 <a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue2844">LWG2844</a> ）。</div>
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<div class="t-li1"><span class="t-li">6)</span> 插入来自 initializer_list <code>ilist</code> 的元素。 若范围中的多个元素拥有比较等价的关键，则插入哪个元素是未指定的（待决的 <a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue2844">LWG2844</a> ）。</div>
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<div class="t-li1"><span class="t-li">7)</span> 若 <code>nh</code> 是空的<a href="cpp-container-node_handle.html">结点把柄</a>，则不做任何事。否则插入 <code>nh</code> 所占有的元素到容器，若容器尚未含有拥有等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">nh.<span class="me1">key</span><span class="br0">(</span><span class="br0">)</span></span></span> 的关键的元素。若 <code>nh</code> 非空且 <span class="t-c"><span class="mw-geshi cpp source-cpp">get_allocator<span class="br0">(</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> nh.<span class="me1">get_allocator</span><span class="br0">(</span><span class="br0">)</span></span></span> 则行为未定义。</div>
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<div class="t-li1"><span class="t-li">8)</span> 若 <code>nh</code> 是空的<a href="cpp-container-node_handle.html">结点把柄</a>，则不做任何事并返回尾迭代器。否则，插入 <code>nh</code> 所占有的元素到容器，若容器尚未含有拥有等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">nh.<span class="me1">key</span><span class="br0">(</span><span class="br0">)</span></span></span> 的关键的元素，并返回指向拥有等于 <span class="t-c"><span class="mw-geshi cpp source-cpp">nh.<span class="me1">key</span><span class="br0">(</span><span class="br0">)</span></span></span> 的关键的元素的迭代器（无关乎插入成功还是失败）。若插入成功，则从 <code>nh</code> 移动，否则它保持该元素的所有权。元素被插入到尽可能接近正好先于 <code>hint</code> 的位置。若 <code>nh</code> 非空且 <span class="t-c"><span class="mw-geshi cpp source-cpp">get_allocator<span class="br0">(</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> nh.<span class="me1">get_allocator</span><span class="br0">(</span><span class="br0">)</span></span></span> 则行为未定义。</div>
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<p>没有迭代器或引用被非法化。<span class="t-rev-inl t-since-cxx17"><span>若插入成功，则在结点把柄保有元素时获得的指向该元素的指针和引用被非法化，而在提取前获得的指向元素的指针和引用变得合法。</span> <span><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></span></span></p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<td>hint</td>
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<td>-</td>
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<td>
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<table class="t-rev-begin">
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<tr class="t-rev t-until-cxx11">
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<td>用作提示从何处开始搜索的迭代器</td>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 前)</span></td>
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</tr>
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<tr class="t-rev t-since-cxx11">
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<td>指向新元素将被插入位置之前的迭代器</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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</table>
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</td>
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<tr class="t-par">
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<td>value</td>
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<td>-</td>
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<td>要插入的元素值</td>
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<tr class="t-par">
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<td>first, last</td>
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<td>-</td>
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<td>要插入的元素范围</td>
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<tr class="t-par">
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<td>ilist</td>
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<td>-</td>
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<td>插入值来源的 initializer_list</td>
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<tr class="t-par">
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<td>nh</td>
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<td>-</td>
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<td>兼容的<a href="cpp-container-node_handle.html">结点把柄</a></td>
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<tr class="t-par-hitem">
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<td colspan="3">类型要求</td>
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<tr class="t-par-req">
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<td colspan="3">-
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<div class="spacer"></div>
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<code>InputIt</code> 必须满足<a href="cpp-named_req-InputIterator.html"><span style="font-style:italic">老式输入迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyInputIterator)</span></a> 的要求。</td>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<div class="t-li1"><span class="t-li">1-2)</span> 返回由指向被插入元素（或阻止插入的元素）的迭代器和若插入发生则设为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 的 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span></span></span> 值。</div>
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<div class="t-li1"><span class="t-li">3-4)</span> 返回指向被插入元素，或阻止插入的元素的迭代器。</div>
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<div class="t-li1"><span class="t-li">5-6)</span> （无）</div>
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<div class="t-li1"><span class="t-li">7)</span> 返回 <code>insert_return_type</code> ，其成员初始化如下：若 <code>nh</code> 为空，则 <code>inserted</code> 为 <code>false</code> ， <code>position</code> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp">end<span class="br0">(</span><span class="br0">)</span></span></span> ，而 <code>node</code> 为空。否则发生插入， <code>inserted</code> 为 <code>true</code> ， <code>position</code> 指向被插入元素，而 <code>node</code> 为空。若插入失败，则 <code>inserted</code> 为 <code>false</code> ， <code>node</code> 拥有 <code>nh</code> 的先前值，而 <code>position</code> 指向拥有等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">nh.<span class="me1">key</span><span class="br0">(</span><span class="br0">)</span></span></span> 的关键的元素。</div>
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<div class="t-li1"><span class="t-li">8)</span> 若 <code>nh</code> 为空则为尾迭代器，若插入发生则为指向被插入元素的迭代器，而若插入失败则为指向拥有等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">nh.<span class="me1">key</span><span class="br0">(</span><span class="br0">)</span></span></span> 的关键的元素的迭代器。</div>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<div class="t-li1"><span class="t-li">1-4)</span> 若任何操作抛异常，则插入无效果。</div>
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<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style="">
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<tr>
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<td class="mbox-empty-cell"></td>
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<td class="mbox-text" style="">本节未完成<br />
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原因：情况 5-8</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">复杂度</span></h3>
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<div class="t-li1"><span class="t-li">1-2)</span> 与容器大小成对数， <code>O(log(size()))</code> 。</div>
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<table class="t-rev-begin">
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<tr class="t-rev t-until-cxx11">
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<div class="t-li1"><span class="t-li">3-4)</span> 若插入恰好发生在正好<i>后于</i> hint 的位置，则为均摊常数，否则与容器大小成对数。</div>
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</td>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 前)</span></td>
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</tr>
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<tr class="t-rev t-since-cxx11">
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<td>
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<div class="t-li1"><span class="t-li">3-4)</span> 若插入恰好发生在正好<i>先于</i> hint 的位置，则为均摊常数，否则与容器大小成对数。</div>
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</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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</table>
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<div class="t-li1"><span class="t-li">5-6)</span> <code>O(N*log(size() + N))</code> ，其中 N 是要插入的元素数。</div>
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<div class="t-li1"><span class="t-li">7)</span> 与容器大小成对数， <code>O(log(size()))</code> 。</div>
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<div class="t-li1"><span class="t-li">8)</span> 若插入恰好发生在正好<i>先于</i> hint 的位置，则为均摊常数，否则与容器大小成对数。</div>
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<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
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<p>有提示插入 <span class="t-v">(3,4)</span> 不返回 bool ，这是为了与顺序容器上的定位插入，如 <span class="t-lc"><a href="cpp-container-vector-insert.html">std::vector::insert</a></span> 签名兼容。这使得可以创建泛型插入器，例如 <span class="t-lc"><a href="cpp-iterator-inserter.html">std::inserter</a></span> 。检查有提示插入是否成功的一种方式是比较插入前后的 <a href="cpp-container-set-size.html">size()</a> 。</p>
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<p>重载 <span class="t-v">(5,6)</span> 通常实现为循环，其中以 <span class="t-lc"><a href="cpp-container-set-end.html">end()</a></span> 为 hint 调用重载 <span class="t-v">(3)</span> ；它们对后附最小元素大于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 中最大元素的有序序列（例如另一 set ）优化。</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <set></span>
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<span class="co2">#include <cassert></span>
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<span class="co2">#include <iostream></span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-container-set.html"><span class="kw1277">std::<span class="me2">set</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> set<span class="sy4">;</span>
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<span class="kw4">auto</span> result_1 <span class="sy1">=</span> set.<span class="me1">insert</span><span class="br0">(</span><span class="nu0">3</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span>result_1.<span class="me1">first</span> <span class="sy3">!</span><span class="sy1">=</span> set.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 它是合法迭代器</span>
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<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span><span class="sy2">*</span>result_1.<span class="me1">first</span> <span class="sy1">==</span> <span class="nu0">3</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span> <span class="br0">(</span>result_1.<span class="me1">second</span><span class="br0">)</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"insert done<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="kw4">auto</span> result_2 <span class="sy1">=</span> set.<span class="me1">insert</span><span class="br0">(</span><span class="nu0">3</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span>result_2.<span class="me1">first</span> <span class="sy1">==</span> result_1.<span class="me1">first</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 相同迭代器</span>
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<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span><span class="sy2">*</span>result_2.<span class="me1">first</span> <span class="sy1">==</span> <span class="nu0">3</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span> <span class="br0">(</span><span class="sy3">!</span>result_2.<span class="me1">second</span><span class="br0">)</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"no insertion<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">insert done
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no insertion</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-container-set-emplace.html"><span class="t-lines"><span>emplace</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>原位构造元素<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-container-set-emplace_hint.html"><span class="t-lines"><span>emplace_hint</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>使用提示原位构造元素<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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</html>
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