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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::pair&lt;T1,T2&gt;::</span>pair</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-pair.html">pair</a></span></div>
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<td rowspan="142">(1)</td>
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<div><span class="mw-geshi cpp source-cpp">pair<span class="br0">(</span><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 &#21069;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> pair<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span><br />
<span class="t-mark">(&#26465;&#20214;&#24615; <code>explicit</code>)</span></td>
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<td rowspan="142">(2)</td>
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<div><span class="mw-geshi cpp source-cpp">pair<span class="br0">(</span> <span class="kw4">const</span> T1<span class="sy3">&amp;</span> x, <span class="kw4">const</span> T2<span class="sy3">&amp;</span> y <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 &#21069;)</span></td>
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<div><span class="mw-geshi cpp source-cpp">pair<span class="br0">(</span> <span class="kw4">const</span> T1<span class="sy3">&amp;</span> x, <span class="kw4">const</span> T2<span class="sy3">&amp;</span> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx14">(C++14 &#21069;)</span><br />
<span class="t-mark">(&#26465;&#20214;&#24615; <code>explicit</code>)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> pair<span class="br0">(</span> <span class="kw4">const</span> T1<span class="sy3">&amp;</span> x, <span class="kw4">const</span> T2<span class="sy3">&amp;</span> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx14">(C++14 &#36215;)</span><br />
<span class="t-mark">(&#26465;&#20214;&#24615; <code>explicit</code>)</span></td>
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<tbody></tbody>
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<td rowspan="142">(3)</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> U1, <span class="kw1">class</span> U2 <span class="sy1">&gt;</span><br />
pair<span class="br0">(</span> U1<span class="sy3">&amp;&amp;</span> x, U2<span class="sy3">&amp;&amp;</span> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx14">(C++14 &#21069;)</span><br />
<span class="t-mark">(&#26465;&#20214;&#24615; <code>explicit</code>)</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> U1, <span class="kw1">class</span> U2 <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> pair<span class="br0">(</span> U1<span class="sy3">&amp;&amp;</span> x, U2<span class="sy3">&amp;&amp;</span> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx14">(C++14 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx23">(C++23 &#21069;)</span><br />
<span class="t-mark">(&#26465;&#20214;&#24615; <code>explicit</code>)</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> U1 <span class="sy1">=</span> T1, <span class="kw1">class</span> U2 <span class="sy1">=</span> T2 <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> pair<span class="br0">(</span> U1<span class="sy3">&amp;&amp;</span> x, U2<span class="sy3">&amp;&amp;</span> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx23">(C++23 &#36215;)</span><br />
<span class="t-mark">(&#26465;&#20214;&#24615; <code>explicit</code>)</span></td>
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<td rowspan="142">(4)</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> U1, <span class="kw1">class</span> U2 <span class="sy1">&gt;</span><br />
pair<span class="br0">(</span> <span class="kw4">const</span> pair<span class="sy1">&lt;</span>U1, U2<span class="sy1">&gt;</span><span class="sy3">&amp;</span> p <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-until-cxx11">(C++11 &#21069;)</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> U1, <span class="kw1">class</span> U2 <span class="sy1">&gt;</span><br />
pair<span class="br0">(</span> <span class="kw4">const</span> pair<span class="sy1">&lt;</span>U1, U2<span class="sy1">&gt;</span><span class="sy3">&amp;</span> p <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx14">(C++14 &#21069;)</span><br />
<span class="t-mark">(&#26465;&#20214;&#24615; <code>explicit</code>)</span></td>
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<tr class="t-dcl t-since-cxx14">
<td>
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> U1, <span class="kw1">class</span> U2 <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> pair<span class="br0">(</span> <span class="kw4">const</span> pair<span class="sy1">&lt;</span>U1, U2<span class="sy1">&gt;</span><span class="sy3">&amp;</span> p <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx14">(C++14 &#36215;)</span><br />
<span class="t-mark">(&#26465;&#20214;&#24615; <code>explicit</code>)</span></td>
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<td rowspan="142">(5)</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> U1, <span class="kw1">class</span> U2 <span class="sy1">&gt;</span><br />
pair<span class="br0">(</span> pair<span class="sy1">&lt;</span>U1, U2<span class="sy1">&gt;</span><span class="sy3">&amp;&amp;</span> p <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx14">(C++14 &#21069;)</span><br />
<span class="t-mark">(&#26465;&#20214;&#24615; <code>explicit</code>)</span></td>
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<tr class="t-dcl t-since-cxx14">
<td>
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> U1, <span class="kw1">class</span> U2 <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> pair<span class="br0">(</span> pair<span class="sy1">&lt;</span>U1, U2<span class="sy1">&gt;</span><span class="sy3">&amp;&amp;</span> p <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx14">(C++14 &#36215;)</span><br />
<span class="t-mark">(&#26465;&#20214;&#24615; <code>explicit</code>)</span></td>
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<td rowspan="142">(6)</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>... <span class="me1">Args1</span>, <span class="kw1">class</span>... <span class="me1">Args2</span> <span class="sy1">&gt;</span><br /></span>
<p>pair<span class="br0">(</span> <a href="cpp-utility-piecewise_construct_t.html"><span class="kw1105">std::<span class="me2">piecewise_construct_t</span></span></a>,<br />
&nbsp; &nbsp; &nbsp; <a href="cpp-utility-tuple.html"><span class="kw1098">std::<span class="me2">tuple</span></span></a><span class="sy1">&lt;</span>Args1...<span class="sy1">&gt;</span> first_args,<br /></p>
&nbsp; &nbsp; &nbsp; <a href="cpp-utility-tuple.html"><span class="kw1098">std::<span class="me2">tuple</span></span></a><span class="sy1">&lt;</span>Args2...<span class="sy1">&gt;</span> second_args <span class="br0">)</span><span class="sy4">;</span></div>
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<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</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>... <span class="me1">Args1</span>, <span class="kw1">class</span>... <span class="me1">Args2</span> <span class="sy1">&gt;</span><br /></span>
<p><span class="kw4">constexpr</span> pair<span class="br0">(</span> <a href="cpp-utility-piecewise_construct_t.html"><span class="kw1105">std::<span class="me2">piecewise_construct_t</span></span></a>,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <a href="cpp-utility-tuple.html"><span class="kw1098">std::<span class="me2">tuple</span></span></a><span class="sy1">&lt;</span>Args1...<span class="sy1">&gt;</span> first_args,<br /></p>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <a href="cpp-utility-tuple.html"><span class="kw1098">std::<span class="me2">tuple</span></span></a><span class="sy1">&lt;</span>Args2...<span class="sy1">&gt;</span> second_args <span class="br0">)</span><span class="sy4">;</span></div>
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<td class="t-dcl-nopad"></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">pair<span class="br0">(</span> <span class="kw4">const</span> pair<span class="sy3">&amp;</span> p <span class="br0">)</span> <span class="sy1">=</span> <span class="kw1">default</span><span class="sy4">;</span></span></div>
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<td>(7)</td>
<td class="t-dcl-nopad"></td>
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<div><span class="mw-geshi cpp source-cpp">pair<span class="br0">(</span> pair<span class="sy3">&amp;&amp;</span> p <span class="br0">)</span> <span class="sy1">=</span> <span class="kw1">default</span><span class="sy4">;</span></span></div>
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<td>(8)</td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<p><br />
&#26500;&#36896;&#26032;&#30340; <code>pair</code> &#12290;</p>
<div class="t-li1"><span class="t-li">1)</span> &#40664;&#35748;&#26500;&#36896;&#20989;&#25968;&#12290;&#20540;&#21021;&#22987;&#21270; pair &#30340;&#20004;&#20010;&#20803;&#32032; <code>first</code> &#21644; <code>second</code> &#12290;
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<ul>
<li>&#27492;&#26500;&#36896;&#20989;&#25968;&#21442;&#19982;&#37325;&#36733;&#20915;&#35758;&#65292;&#24403;&#19988;&#20165;&#24403; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_default_constructible.html"><span class="kw527">std::<span class="me2">is_default_constructible_v</span></span></a><span class="sy1">&lt;</span>first_type<span class="sy1">&gt;</span></span></span> &#19982; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_default_constructible.html"><span class="kw527">std::<span class="me2">is_default_constructible_v</span></span></a><span class="sy1">&lt;</span>second_type<span class="sy1">&gt;</span></span></span> &#22343;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#12290;</li>
<li>&#27492;&#26500;&#36896;&#20989;&#25968;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span></span></span> &#65292;&#24403;&#19988;&#20165;&#24403; <code>first_type</code> &#25110; <code>second_type</code> &#19981;&#21487;&#38544;&#24335;&#40664;&#35748;&#26500;&#36896;&#12290;</li>
</ul>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<div class="t-li1"><span class="t-li">2)</span> &#20197; <code>x</code> &#21021;&#22987;&#21270; <code>first</code> &#24182;&#20197; <code>y</code> &#21021;&#22987;&#21270; <code>second</code> &#12290;
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<li>&#27492;&#26500;&#36896;&#20989;&#25968;&#21442;&#19982;&#37325;&#36733;&#20915;&#35758;&#65292;&#24403;&#19988;&#20165;&#24403; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_copy_constructible.html"><span class="kw533">std::<span class="me2">is_copy_constructible_v</span></span></a><span class="sy1">&lt;</span>first_type<span class="sy1">&gt;</span></span></span> &#19982; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_copy_constructible.html"><span class="kw533">std::<span class="me2">is_copy_constructible_v</span></span></a><span class="sy1">&lt;</span>second_type<span class="sy1">&gt;</span></span></span> &#22343;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#12290;</li>
<li>&#27492;&#26500;&#36896;&#20989;&#25968;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span></span></span> &#65292;&#24403;&#19988;&#20165;&#24403; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_convertible.html"><span class="kw593">std::<span class="me2">is_convertible_v</span></span></a><span class="sy1">&lt;</span><span class="kw4">const</span> first_type<span class="sy3">&amp;</span>, first_type<span class="sy1">&gt;</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#25110; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_convertible.html"><span class="kw593">std::<span class="me2">is_convertible_v</span></span></a><span class="sy1">&lt;</span><span class="kw4">const</span> second_type<span class="sy3">&amp;</span>, second_type<span class="sy1">&gt;</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#12290;</li>
</ul>
</td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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</div>
<div class="t-li1"><span class="t-li">3)</span> &#20197; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1">&lt;</span>U1<span class="sy1">&gt;</span><span class="br0">(</span>x<span class="br0">)</span></span></span> &#21021;&#22987;&#21270; <code>first</code> &#24182;&#20197; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1">&lt;</span>U2<span class="sy1">&gt;</span><span class="br0">(</span>y<span class="br0">)</span></span></span> &#21021;&#22987;&#21270; <code>second</code> &#12290;
<ul>
<li>&#27492;&#26500;&#36896;&#20989;&#25968;&#21442;&#19982;&#37325;&#36733;&#20915;&#35758;&#65292;&#24403;&#19988;&#20165;&#24403; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_constructible.html"><span class="kw521">std::<span class="me2">is_constructible_v</span></span></a><span class="sy1">&lt;</span>first_type, U1<span class="sy3">&amp;&amp;</span><span class="sy1">&gt;</span></span></span> &#21644; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_constructible.html"><span class="kw521">std::<span class="me2">is_constructible_v</span></span></a><span class="sy1">&lt;</span>second_type, U2<span class="sy3">&amp;&amp;</span><span class="sy1">&gt;</span></span></span> &#22343;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#12290;</li>
<li>&#27492;&#26500;&#36896;&#20989;&#25968;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span></span></span> &#65292;&#24403;&#19988;&#20165;&#24403; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_convertible.html"><span class="kw593">std::<span class="me2">is_convertible_v</span></span></a><span class="sy1">&lt;</span>U1<span class="sy3">&amp;&amp;</span>, first_type<span class="sy1">&gt;</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#25110; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_convertible.html"><span class="kw593">std::<span class="me2">is_convertible_v</span></span></a><span class="sy1">&lt;</span>U2<span class="sy3">&amp;&amp;</span>, second_type<span class="sy1">&gt;</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#12290;</li>
</ul>
</div>
<div class="t-li1"><span class="t-li">4)</span> &#20197; <code>p.first</code> &#21021;&#22987;&#21270; <code>first</code> &#24182;&#20197; <code>p.second</code> &#21021;&#22987;&#21270; <code>second</code> &#12290;
<table class="t-rev-begin">
<tr class="t-rev t-since-cxx11">
<td>
<ul>
<li>&#27492;&#26500;&#36896;&#20989;&#25968;&#21442;&#19982;&#37325;&#36733;&#20915;&#35758;&#65292;&#24403;&#19988;&#20165;&#24403; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_constructible.html"><span class="kw521">std::<span class="me2">is_constructible_v</span></span></a><span class="sy1">&lt;</span>first_type, <span class="kw4">const</span> U1<span class="sy3">&amp;</span><span class="sy1">&gt;</span></span></span> &#21644; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_constructible.html"><span class="kw521">std::<span class="me2">is_constructible_v</span></span></a><span class="sy1">&lt;</span>second_type, <span class="kw4">const</span> U2<span class="sy3">&amp;</span><span class="sy1">&gt;</span></span></span> &#22343;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#12290;</li>
<li>&#27492;&#26500;&#36896;&#20989;&#25968;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span></span></span> &#65292;&#24403;&#19988;&#20165;&#24403; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_convertible.html"><span class="kw593">std::<span class="me2">is_convertible_v</span></span></a><span class="sy1">&lt;</span><span class="kw4">const</span> U1<span class="sy3">&amp;</span>, first_type<span class="sy1">&gt;</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#25110; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_convertible.html"><span class="kw593">std::<span class="me2">is_convertible_v</span></span></a><span class="sy1">&lt;</span><span class="kw4">const</span> U2<span class="sy3">&amp;</span>, second_type<span class="sy1">&gt;</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#12290;</li>
</ul>
</td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
</tr>
</table>
</div>
<div class="t-li1"><span class="t-li">5)</span> &#20197; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1">&lt;</span>U1<span class="sy1">&gt;</span><span class="br0">(</span>p.<span class="me1">first</span><span class="br0">)</span></span></span> &#21021;&#22987;&#21270; <code>first</code> &#24182;&#20197; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1">&lt;</span>U2<span class="sy1">&gt;</span><span class="br0">(</span>p.<span class="me1">second</span><span class="br0">)</span></span></span> &#21021;&#22987;&#21270; <code>second</code> &#12290;
<ul>
<li>&#27492;&#26500;&#36896;&#20989;&#25968;&#21442;&#19982;&#37325;&#36733;&#20915;&#35758;&#65292;&#24403;&#19988;&#20165;&#24403; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_constructible.html"><span class="kw521">std::<span class="me2">is_constructible_v</span></span></a><span class="sy1">&lt;</span>first_type, U1<span class="sy3">&amp;&amp;</span><span class="sy1">&gt;</span></span></span> &#21644; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_constructible.html"><span class="kw521">std::<span class="me2">is_constructible_v</span></span></a><span class="sy1">&lt;</span>second_type, U2<span class="sy3">&amp;&amp;</span><span class="sy1">&gt;</span></span></span> &#22343;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#12290;</li>
<li>&#27492;&#26500;&#36896;&#20989;&#25968;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span></span></span> &#65292;&#24403;&#19988;&#20165;&#24403; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_convertible.html"><span class="kw593">std::<span class="me2">is_convertible_v</span></span></a><span class="sy1">&lt;</span>U1<span class="sy3">&amp;&amp;</span>, first_type<span class="sy1">&gt;</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#25110; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_convertible.html"><span class="kw593">std::<span class="me2">is_convertible_v</span></span></a><span class="sy1">&lt;</span>U2<span class="sy3">&amp;&amp;</span>, second_type<span class="sy1">&gt;</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#12290;</li>
</ul>
</div>
<div class="t-li1"><span class="t-li">6)</span> &#36716;&#21457; <code>first_args</code> &#30340;&#20803;&#32032;&#21040; <code>first</code> &#30340;&#26500;&#36896;&#20989;&#25968;&#24182;&#36716;&#21457; <code>second_args</code> &#30340;&#20803;&#32032;&#21040; <code>second</code> &#30340;&#26500;&#36896;&#20989;&#25968;&#12290;&#36825;&#26159;&#33021;&#29992;&#20110;&#26500;&#36896;&#19981;&#21487;&#22797;&#21046;&#19981;&#21487;&#31227;&#21160;&#31867;&#22411;&#30340; pair &#30340;&#20165;&#26377;&#30340;&#38750;&#40664;&#35748;&#26500;&#36896;&#20989;&#25968;&#12290;</div>
<div class="t-li1"><span class="t-li">7)</span> &#22797;&#21046;&#26500;&#36896;&#20989;&#25968;&#20026;<span class="t-rev-inl t-until-cxx11"><span>&#38544;&#24335;&#22768;&#26126;</span> <span><span class="t-mark-rev t-until-cxx11">(C++11 &#21069;)</span></span></span><span class="t-rev-inl t-since-cxx11"><span>&#40664;&#35748;&#21270;&#65292;&#19988;&#33509;&#20004;&#20010;&#20803;&#32032;&#30340;&#22797;&#21046;&#28385;&#36275; constexpr &#20989;&#25968;&#30340;&#35201;&#27714;&#21017;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span></span></span></span> <span><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></span></span>&#12290;</div>
<div class="t-li1"><span class="t-li">8)</span> &#31227;&#21160;&#26500;&#36896;&#20989;&#25968;&#20026;&#40664;&#35748;&#21270;&#65292;&#19988;&#33509;&#20004;&#20010;&#20803;&#32032;&#30340;&#31227;&#21160;&#28385;&#36275; constexpr &#20989;&#25968;&#30340;&#35201;&#27714;&#21017;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span></span></span> &#12290;</div>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
<table class="t-par-begin">
<tr class="t-par">
<td>x</td>
<td>-</td>
<td>&#21021;&#22987;&#21270;&#27492; pair &#39318;&#20803;&#32032;&#30340;&#20540;</td>
</tr>
<tr class="t-par">
<td>y</td>
<td>-</td>
<td>&#21021;&#22987;&#21270;&#27492; pair &#31532;&#20108;&#20803;&#32032;&#30340;&#20540;</td>
</tr>
<tr class="t-par">
<td>p</td>
<td>-</td>
<td>&#29992;&#20110;&#21021;&#22987;&#21270;&#27492; pair &#20004;&#20010;&#20803;&#32032;&#30340;&#20540;&#30340; pair</td>
</tr>
<tr class="t-par">
<td>first_args</td>
<td>-</td>
<td>&#21021;&#22987;&#21270;&#27492; pair &#39318;&#20803;&#32032;&#30340;&#26500;&#36896;&#20989;&#25968;&#21442;&#25968;&#30340; tuple</td>
</tr>
<tr class="t-par">
<td>second_args</td>
<td>-</td>
<td>&#21021;&#22987;&#21270;&#27492; pair &#31532;&#20108;&#20803;&#32032;&#30340;&#26500;&#36896;&#20989;&#25968;&#21442;&#25968;&#30340; tuple</td>
</tr>
</table>
<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">&#24322;&#24120;</span></h3>
<p>&#19981;&#25243;&#24322;&#24120;&#65292;&#38500;&#38750;&#25351;&#23450;&#25805;&#20316;&#20043;&#19968;&#65288;&#22914;&#20803;&#32032;&#30340;&#26500;&#36896;&#65289;&#25243;&#20986;&#12290;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
<div class="t-example">
<div class="t-example-live-link"></div>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="cpp source-cpp">
<pre class="de1"><span class="co2">#include &lt;utility&gt;</span>
<span class="co2">#include &lt;string&gt;</span>
<span class="co2">#include &lt;complex&gt;</span>
<span class="co2">#include &lt;tuple&gt;</span>
<span class="co2">#include &lt;iostream&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw4">auto</span> print <span class="sy1">=</span> <span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">auto</span> rem, <span class="kw4">auto</span> <span class="kw4">const</span><span class="sy3">&amp;</span> pair<span class="br0">)</span> <span class="br0">{</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> rem <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;(&quot;</span> <span class="sy1">&lt;&lt;</span> pair.<span class="me1">first</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;, &quot;</span> <span class="sy1">&lt;&lt;</span> pair.<span class="me1">second</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;)<span class="es1">\n</span>&quot;</span><span class="sy4">;</span>
<span class="br0">}</span><span class="sy4">;</span>
<a href="cpp-utility-pair.html"><span class="kw1096">std::<span class="me2">pair</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span>, <span class="kw4">float</span><span class="sy1">&gt;</span> p1<span class="sy4">;</span>
print<span class="br0">(</span><span class="st0">&quot;(1) Value-initialized: &quot;</span>, p1<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-utility-pair.html"><span class="kw1096">std::<span class="me2">pair</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span>, <span class="kw4">double</span><span class="sy1">&gt;</span> p2<span class="br0">{</span><span class="nu0">42</span>, <span class="nu16">3.1415</span><span class="br0">}</span><span class="sy4">;</span>
print<span class="br0">(</span><span class="st0">&quot;(2) Initialized with two values: &quot;</span>, p2<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-utility-pair.html"><span class="kw1096">std::<span class="me2">pair</span></span></a><span class="sy1">&lt;</span><span class="kw4">char</span>, <span class="kw4">int</span><span class="sy1">&gt;</span> p4<span class="br0">{</span>p2<span class="br0">}</span><span class="sy4">;</span>
print<span class="br0">(</span><span class="st0">&quot;(4) Implicitly converted: &quot;</span>, p4<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-utility-pair.html"><span class="kw1096">std::<span class="me2">pair</span></span></a><span class="sy1">&lt;</span><a href="cpp-numeric-complex.html"><span class="kw1472">std::<span class="me2">complex</span></span></a><span class="sy1">&lt;</span><span class="kw4">double</span><span class="sy1">&gt;</span>, <a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a><span class="sy1">&gt;</span> p6<span class="br0">{</span>
<a href="cpp-utility-piecewise_construct.html"><span class="kw1106">std::<span class="me2">piecewise_construct</span></span></a>,
<a href="cpp-utility-tuple-forward_as_tuple.html"><span class="kw1114">std::<span class="me2">forward_as_tuple</span></span></a><span class="br0">(</span><span class="nu16">0.123</span>, <span class="nu16">7.7</span><span class="br0">)</span>,
<a href="cpp-utility-tuple-forward_as_tuple.html"><span class="kw1114">std::<span class="me2">forward_as_tuple</span></span></a><span class="br0">(</span><span class="nu0">10</span>, <span class="st0">&#39;a&#39;</span><span class="br0">)</span><span class="br0">}</span><span class="sy4">;</span>
print<span class="br0">(</span><span class="st0">&quot;(6) Piecewise constructed: &quot;</span>, p6<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
</div>
<p>&#21487;&#33021;&#30340;&#36755;&#20986;&#65306;</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="text source-text">
<pre class="de1">(1) Value-initialized: (0, 0)
(2) Initialized with two values: (42, 3.1415)
(4) Implicitly converted: (*, 3)
(6) Piecewise constructed: ((0.123,7.7), aaaaaaaaaa)</pre></div>
</div>
</div>
<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">&#32570;&#38519;&#25253;&#21578;</span></h3>
<p>&#19979;&#21015;&#26356;&#25913;&#34892;&#20026;&#30340;&#32570;&#38519;&#25253;&#21578;&#36861;&#28335;&#22320;&#24212;&#29992;&#20110;&#20197;&#21069;&#20986;&#29256;&#30340; C++ &#26631;&#20934;&#12290;</p>
<table class="dsctable" style="font-size:0.8em">
<tr>
<th>DR</th>
<th>&#24212;&#29992;&#20110;</th>
<th>&#20986;&#29256;&#26102;&#30340;&#34892;&#20026;</th>
<th>&#27491;&#30830;&#34892;&#20026;</th>
</tr>
<tr>
<td><a rel="nofollow" class="external text" href="https://wg21.link/N4387">N4387</a></td>
<td>C++11</td>
<td>&#26576;&#20123;&#26500;&#36896;&#20989;&#25968;&#26366;&#20026; explicit &#65292;&#38459;&#27490;&#20102;&#26377;&#29992;&#30340;&#34892;&#20026;</td>
<td>&#20351;&#22823;&#22810;&#25968;&#26500;&#36896;&#20989;&#25968;&#20026;&#26465;&#20214;&#24615; explicit</td>
</tr>
<tr>
<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue2510">LWG 2510</a></td>
<td>C++11</td>
<td>&#40664;&#35748;&#26500;&#36896;&#20989;&#25968;&#20026;&#38544;&#24335;</td>
<td>&#20351;&#20043;&#20026;&#26465;&#20214;&#24615; explicit</td>
</tr>
</table>
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
<table class="t-dsc-begin">
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-utility-pair-make_pair.html"><span class="t-lines"><span>make_pair</span></span></a></div>
</div>
</td>
<td>&#21019;&#24314;&#19968;&#20010; <code>pair</code> &#23545;&#35937;&#65292;&#20854;&#31867;&#22411;&#26681;&#25454;&#21508;&#23454;&#21442;&#31867;&#22411;&#23450;&#20041;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
</tr>
</table>
</div>
<div class="visualClear"></div>
</div>
</div>
</div>
</body>
</html>
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