224 lines
11 KiB
HTML
224 lines
11 KiB
HTML
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<title>std::pair</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_utility_pair 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::</span>pair</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-utility.html">utility</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-utility.html"><utility></a></code></div>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><br /></span>
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<p> <span class="kw1">class</span> T1,<br />
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<span class="kw1">class</span> T2<br /></p>
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<span class="sy1">></span> <span class="kw1">struct</span> pair<span class="sy4">;</span></div>
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<p><code>std::pair</code> 是类模板，提供在一个单元存储两个相异类型对象的途径。 <code>pair</code> 是 <span class="t-lc"><a href="cpp-utility-tuple.html">std::tuple</a></span> 的拥有两个元素的特殊情况。</p>
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<p>若 <code>T1</code> 与 <code>T2</code> 都不是可能有 cv 限定的拥有非平凡析构函数的类类型，或其数组，则 <code>pair</code> 的析构函数为平凡。</p>
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<h3><span class="mw-headline" id=".E6.A8.A1.E6.9D.BF.E5.BD.A2.E5.8F.82">模板形参</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>T1, T2</td>
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<td>-</td>
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<td>pair 所存储的元素类型。</td>
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</table>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B">成员类型</span></h3>
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<table class="t-dsc-begin">
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<td>成员类型</td>
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<td>定义</td>
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<tr class="t-dsc">
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<td><code>first_type</code></td>
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<td><code>T1</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>second_type</code></td>
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<td><code>T2</code></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.AF.B9.E8.B1.A1">成员对象</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc-hitem">
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<td>成员名</td>
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<td>类型</td>
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<tr class="t-dsc">
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<td><code>first</code></td>
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<td><code>T1</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>second</code></td>
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<td><code>T2</code></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">成员函数</span></h3>
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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-utility-pair-pair.html"><span class="t-lines"><span>(构造函数)</span></span></a></div>
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</div>
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</td>
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<td>构造新的 pair<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-utility-pair-operator=.html"><span class="t-lines"><span>operator=</span></span></a></div>
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</div>
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</td>
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<td>对 内容赋值<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-utility-pair-swap.html"><span class="t-lines"><span>swap</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>交换内容<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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<h3><span class="mw-headline" id=".E9.9D.9E.E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">非成员函数</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-utility-pair-make_pair.html"><span class="t-lines"><span>make_pair</span></span></a></div>
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</div>
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</td>
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<td>创建一个 <code>pair</code> 对象，其类型根据各实参类型定义<br />
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<span class="t-mark">(函数模板)</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-utility-pair-operator_cmp.html"><span class="t-lines"><span>operator==</span><span>operator!=</span><span>operator<</span><span>operator<=</span><span>operator></span><span>operator>=</span><span>operator<=></span></span></a></div>
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<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-until-cxx20">(C++20 中移除)</span></span><span><span class="t-mark-rev t-until-cxx20">(C++20 中移除)</span></span><span><span class="t-mark-rev t-until-cxx20">(C++20 中移除)</span></span><span><span class="t-mark-rev t-until-cxx20">(C++20 中移除)</span></span><span><span class="t-mark-rev t-until-cxx20">(C++20 中移除)</span></span><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>按字典序比较 pair 中的值<br />
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<span class="t-mark">(函数模板)</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-utility-pair-swap2.html"><span class="t-lines"><span>std::swap<span class="t-dsc-small">(std::pair)</span></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>特化 <span class="t-lc"><a href="cpp-algorithm-swap.html">std::swap</a></span> 算法<br />
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<span class="t-mark">(函数模板)</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-utility-pair-get.html"><span class="t-lines"><span>std::get<span class="t-dsc-small">(std::pair)</span></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>访问 <code>pair</code> 的一个元素<br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BE.85.E5.8A.A9.E7.B1.BB">辅助类</span></h3>
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<table class="t-dsc-begin">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-utility-pair-tuple_size.html"><span class="t-lines"><span>std::tuple_size<span class="t-dsc-small"><std::pair></span></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>获得 <code>pair</code> 的大小<br />
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<span class="t-mark">(类模板特化)</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-utility-pair-tuple_element.html"><span class="t-lines"><span>std::tuple_element<span class="t-dsc-small"><std::pair></span></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>获得 <code>pair</code> 中元素的类型<br />
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<span class="t-mark">(类模板特化)</span></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E6.8E.A8.E5.AF.BC.E6.8C.87.E5.BC.95.28C.2B.2B17_.E8.B5.B7.29"><a href="cpp-utility-pair-deduction_guides.html">推导指引</a><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></span></h3>
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<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">缺陷报告</span></h3>
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<p>下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。</p>
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<table class="dsctable" style="font-size:0.8em">
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<tr>
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<th>DR</th>
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<th>应用于</th>
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<th>出版时的行为</th>
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<th>正确行为</th>
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</tr>
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<tr>
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<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue2796">LWG 2796</a></td>
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<td>C++98</td>
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<td><code>pair</code> 的析构函数的平凡性未指明</td>
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<td>已指明</td>
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</tr>
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</table>
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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-utility-tuple.html"><span class="t-lines"><span>tuple</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>实现固定大小的容器，它保有类型可以相异的元素<br />
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<span class="t-mark">(类模板)</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-utility-tuple-tie.html"><span class="t-lines"><span>tie</span></span></a></div>
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</div>
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</td>
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<td>创建左值引用的 <code>tuple</code>，或将 tuple 解包为独立对象<br />
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<span class="t-mark">(函数模板)</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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