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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>unwrap_reference, <span style="font-size:0.7em; line-height:130%">std::</span>unwrap_ref_decay</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-utility.html">utility</a>&lrm; | <a href="cpp-utility-functional.html">functional</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-type_traits.html">&lt;type_traits&gt;</a></code></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-functional.html">&lt;functional&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> T <span class="sy1">&gt;</span><br />
<span class="kw1">struct</span> unwrap_reference<span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> T <span class="sy1">&gt;</span><br />
<span class="kw1">struct</span> unwrap_ref_decay<span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<div class="t-li1"><span class="t-li">1)</span> &#33509; <code>T</code> &#20026;&#26576;&#31867;&#22411; <code>U</code> &#30340; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-functional-reference_wrapper.html"><span class="kw1068">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1">&lt;</span>U<span class="sy1">&gt;</span></span></span> &#65292;&#21017;&#25552;&#20379;&#25351;&#21517; <code>U&amp;</code> &#30340;&#25104;&#21592; typedef <code>type</code> &#65307;&#21542;&#21017;&#25552;&#20379;&#25351;&#21517; <code>T</code> &#30340;&#25104;&#21592; typedef <code>type</code> &#12290;</div>
<div class="t-li1"><span class="t-li">2)</span> &#33509; <code>T</code> &#20026;&#26576;&#31867;&#22411; <code>U</code> &#30340; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-functional-reference_wrapper.html"><span class="kw1068">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1">&lt;</span>U<span class="sy1">&gt;</span></span></span> &#65292;&#24573;&#30053; cv &#38480;&#23450;&#21644;&#24341;&#29992;&#65292;&#21017;&#25552;&#20379;&#25351;&#21517; <code>U&amp;</code> &#30340;&#25104;&#21592; typedef <code>type</code> &#65307;&#21542;&#21017;&#25552;&#20379;&#25351;&#21517; <code>std::decay_t&lt;T&gt;</code> &#30340;&#25104;&#21592; typedef <code>type</code> &#12290;</div>
<p>&#28155;&#21152;&#27492;&#39029;&#38754;&#19978;&#25551;&#36848;&#30340;&#20219;&#20309;&#27169;&#26495;&#30340;&#29305;&#21270;&#30340;&#31243;&#24207;&#34892;&#20026;&#26410;&#23450;&#20041;&#12290;</p>
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B">&#25104;&#21592;&#31867;&#22411;</span></h3>
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<p>1) &#33509; <code>T</code> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-functional-reference_wrapper.html"><span class="kw1068">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1">&lt;</span>U<span class="sy1">&gt;</span></span></span> &#21017;&#20026; <code>U&amp;</code> &#65307;&#21542;&#21017;&#20026; <code>T</code></p>
<p>2) &#33509; <code>std::decay_t&lt;T&gt;</code> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-functional-reference_wrapper.html"><span class="kw1068">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1">&lt;</span>U<span class="sy1">&gt;</span></span></span> &#21017;&#20026; <code>U&amp;</code> &#65307;&#21542;&#21017;&#20026; <code>std::decay_t&lt;T&gt;</code></p>
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<h3><span class="mw-headline" id=".E8.BE.85.E5.8A.A9.E7.B1.BB.E5.9E.8B">&#36741;&#21161;&#31867;&#22411;</span></h3>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> T<span class="sy1">&gt;</span><br />
<span class="kw1">using</span> unwrap_reference_t <span class="sy1">=</span> <span class="kw1">typename</span> unwrap_reference<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">type</span><span class="sy4">;</span></span></div>
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<td>(1)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> T<span class="sy1">&gt;</span><br />
<span class="kw1">using</span> unwrap_ref_decay_t <span class="sy1">=</span> <span class="kw1">typename</span> unwrap_ref_decay<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">type</span><span class="sy4">;</span></span></div>
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<td>(2)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<h3><span class="mw-headline" id=".E5.8F.AF.E8.83.BD.E7.9A.84.E5.AE.9E.E7.8E.B0">&#21487;&#33021;&#30340;&#23454;&#29616;</span></h3>
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<pre class="de1"><span class="kw1">template</span> <span class="sy1">&lt;</span><span class="kw1">class</span> T<span class="sy1">&gt;</span>
<span class="kw1">struct</span> unwrap_reference <span class="br0">{</span> <span class="kw1">using</span> type <span class="sy1">=</span> T<span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span>
<span class="kw1">template</span> <span class="sy1">&lt;</span><span class="kw1">class</span> U<span class="sy1">&gt;</span>
<span class="kw1">struct</span> unwrap_reference<span class="sy1">&lt;</span><a href="cpp-utility-functional-reference_wrapper.html"><span class="kw1068">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1">&lt;</span>U<span class="sy1">&gt;&gt;</span> <span class="br0">{</span> <span class="kw1">using</span> type <span class="sy1">=</span> U<span class="sy3">&amp;</span><span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span>
<span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> T <span class="sy1">&gt;</span>
<span class="kw1">struct</span> unwrap_ref_decay <span class="sy4">:</span> std<span class="sy4">::</span><span class="me2">unwrap_reference</span><span class="sy1">&lt;</span><a href="cpp-types-decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;&gt;</span> <span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span></pre></div>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<p><code>std::unwrap_ref_decay</code> &#36827;&#34892;&#19982; <span class="t-lc"><a href="cpp-utility-pair-make_pair.html">std::make_pair</a></span> &#21450; <span class="t-lc"><a href="cpp-utility-tuple-make_tuple.html">std::make_tuple</a></span> &#25152;&#29992;&#32773;&#30456;&#21516;&#30340;&#21464;&#25442;&#12290;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
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<div><a href="cpp-utility-functional-reference_wrapper.html"><span class="t-lines"><span>reference_wrapper</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td><a href="cpp-named_req-CopyConstructible.html"><span style="font-style:italic">&#21487;&#22797;&#21046;&#26500;&#36896;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(CopyConstructible)</span></a> &#19988;<a href="cpp-named_req-CopyAssignable.html"><span style="font-style:italic">&#21487;&#22797;&#21046;&#36171;&#20540;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(CopyAssignable)</span></a> &#30340;&#24341;&#29992;&#21253;&#35013;&#22120;<br />
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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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<td>&#21019;&#24314;&#19968;&#20010; <code>pair</code> &#23545;&#35937;&#65292;&#20854;&#31867;&#22411;&#26681;&#25454;&#21508;&#23454;&#21442;&#31867;&#22411;&#23450;&#20041;<br />
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<div><a href="cpp-utility-tuple-make_tuple.html"><span class="t-lines"><span>make_tuple</span></span></a></div>
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<td>&#21019;&#24314;&#19968;&#20010; <code>tuple</code> &#23545;&#35937;&#65292;&#20854;&#31867;&#22411;&#26681;&#25454;&#21508;&#23454;&#21442;&#31867;&#22411;&#23450;&#20041;<br />
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