73 lines
4.7 KiB
HTML
73 lines
4.7 KiB
HTML
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<title>std::move_constructible</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_concepts_move_constructible 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>move_constructible</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-concepts.html">concepts</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-concepts.html"><concepts></a></code></div>
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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> T <span class="sy1">></span><br />
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concept move_constructible <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">constructible_from</span><span class="sy1"><</span>T, T<span class="sy1">></span> <span class="sy3">&&</span> std<span class="sy4">::</span><span class="me2">convertible_to</span><span class="sy1"><</span>T, T<span class="sy1">></span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<p>概念 <code>move_constructible</code> 若符合这些条件则得到满足， <code>T</code> 为引用类型，或它是对象类型，并且能在直接和复制初始化语境中，以通常语义从该类型右值构造该类型对象。</p>
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<h3><span class="mw-headline" id=".E8.AF.AD.E4.B9.89.E8.A6.81.E6.B1.82">语义要求</span></h3>
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<p>若 <code>T</code> 是对象类型，则 <code>move_constructible<T></code> 仅若符合下列条件才得到实现。给定</p>
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<li><code>rv</code> ， <code>T</code> 类型右值，和</li>
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<li><code>u2</code> ，等于 <code>rv</code> 的 <code>T</code> 类型不同对象，</li>
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<p>下列为真：</p>
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<li>在定义 <span class="t-c"><span class="mw-geshi cpp source-cpp">T u <span class="sy1">=</span> rv<span class="sy4">;</span></span></span> 后， <code>u</code> 等于 <code>u2</code> ；</li>
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<li><code>T(rv)</code> 等于 <code>u2</code> ；且</li>
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<li>若 <code>T</code> 无 const 限定，则 <code>rv</code> 的结果状态（在上述任一条中求值的定义/表达式后）合法但未指定；否则不更改它。</li>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<div><a href="cpp-types-is_move_constructible.html"><span class="t-lines"><span>is_move_constructible</span><span>is_trivially_move_constructible</span><span>is_nothrow_move_constructible</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><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>检查类型是否能从右值引用构造<br />
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<span class="t-mark">(类模板)</span></td>
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