96 lines
5.9 KiB
HTML
96 lines
5.9 KiB
HTML
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<title>std::experimental::ranges::exchange</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_experimental_ranges_utility_exchange 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::experimental::ranges::</span>exchange</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-experimental.html">experimental</a>‎ | <a href="cpp-experimental-ranges.html">ranges</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-experimental-ranges-utility.html"><experimental/ranges/utility></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <a href="cpp-experimental-ranges-concepts-MoveConstructible.html"><span class="kw2550">ranges::<span class="me2">MoveConstructible</span></span></a> T, <span class="kw1">class</span> U <span class="sy1">=</span> T <span class="sy1">></span><br /></span>
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<p> requires <a href="cpp-experimental-ranges-concepts-Assignable.html"><span class="kw2538">ranges::<span class="me2">Assignable</span></span></a><span class="sy1"><</span>T<span class="sy3">&</span>, U<span class="sy1">></span><br /></p>
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<span class="kw4">constexpr</span> T exchange<span class="br0">(</span>T<span class="sy3">&</span> obj, U<span class="sy3">&&</span> new_val<span class="br0">)</span> <span class="kw1">noexcept</span><span class="br0">(</span><span class="coMULTI">/* see below */</span><span class="br0">)</span><span class="sy4">;</span></div>
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<td><span class="t-mark-rev t-since-ranges-ts t-mark-ts">(范围 TS)</span></td>
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<p>以 <code>new_value</code> 替换 <code>obj</code> 的值并返回 <code>obj</code> 的旧值，如同用以下方式</p>
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<div class="cpp source-cpp">
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<pre class="de1">T old_value <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>obj<span class="br0">)</span><span class="sy4">;</span>
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obj <span class="sy1">=</span> <a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="br0">(</span>new_value<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">return</span> old_value<span class="sy4">;</span></pre></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<td>obj</td>
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<td>-</td>
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<td>要替换其值的对象</td>
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<td>new_value</td>
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<td>-</td>
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<td>要赋给 <code>obj</code> 的值</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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<p><code>obj</code> 的旧值。</p>
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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-noexcept-full"><a href="cpp-language-noexcept_spec.html"><tt>noexcept</tt></a> 说明：
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<div class="t-noexcept-box"><span class="t-cc"><span class="mw-geshi cpp source-cpp"><span class="kw1">noexcept</span><span class="br0">(</span><a href="cpp-types-is_move_constructible.html"><span class="kw542">std::<span class="me2">is_nothrow_move_constructible</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy4">::</span><span class="me2">value</span> <span class="sy3">&&</span><br />
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<a href="cpp-types-is_assignable.html"><span class="kw548">std::<span class="me2">is_nothrow_assignable</span></span></a><span class="sy1"><</span>T<span class="sy3">&</span>, U<span class="sy1">></span><span class="sy4">::</span><span class="me2">value</span><span class="br0">)</span></span></span></div>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<td class="mbox-text" style="">本节未完成<br />
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原因：暂无示例</td>
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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-utility-exchange.html"><span class="t-lines"><span>exchange</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx14">(C++14)</span></span></span></div>
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<td>将实参替换为一个新值，并返回其先前值<br />
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<span class="t-mark">(函数模板)</span></td>
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