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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::ranges::</span>copy, <span style="font-size:0.7em; line-height:130%">std::ranges::</span>copy_if, <span style="font-size:0.7em; line-height:130%">std::ranges::</span>copy_result, <span style="font-size:0.7em; line-height:130%">std::ranges::</span>copy_if_result</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-algorithm.html">algorithm</a>&lrm; | <a href="cpp-algorithm-ranges.html">ranges</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-algorithm.html">&lt;algorithm&gt;</a></code></div>
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<div>&#35843;&#29992;&#31614;&#21517;</div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> std<span class="sy4">::</span><span class="me2">input_iterator</span> I, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1">&lt;</span>I<span class="sy1">&gt;</span> S, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O <span class="sy1">&gt;</span><br /></span>
<p>requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1">&lt;</span>I, O<span class="sy1">&gt;</span><br /></p>
<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">copy_result</span><span class="sy1">&lt;</span>I, O<span class="sy1">&gt;</span> copy<span class="br0">(</span> I first, S last, O result <span class="br0">)</span><span class="sy4">;</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> ranges<span class="sy4">::</span><span class="me2">input_range</span> R, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O <span class="sy1">&gt;</span><br /></span>
<p>requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1">&lt;</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1">&lt;</span>R<span class="sy1">&gt;</span>, O<span class="sy1">&gt;</span><br />
&nbsp; <span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">copy_result</span><span class="sy1">&lt;</span>ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1">&lt;</span>R<span class="sy1">&gt;</span>, O<span class="sy1">&gt;</span><br /></p>
copy<span class="br0">(</span> R<span class="sy3">&amp;&amp;</span> r, O result <span class="br0">)</span><span class="sy4">;</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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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> std<span class="sy4">::</span><span class="me2">input_iterator</span> I, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1">&lt;</span>I<span class="sy1">&gt;</span> S, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O,<br /></span>
<p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; std<span class="sy4">::</span><span class="me2">indirect_unary_predicate</span><span class="sy1">&lt;</span>std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1">&lt;</span>I, Proj<span class="sy1">&gt;&gt;</span> Pred <span class="sy1">&gt;</span><br />
requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1">&lt;</span>I, O<span class="sy1">&gt;</span><br />
&nbsp; <span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">copy_if_result</span><span class="sy1">&lt;</span>I, O<span class="sy1">&gt;</span><br /></p>
copy_if<span class="br0">(</span> I first, S last, O result, Pred pred, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(3)</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> ranges<span class="sy4">::</span><span class="me2">input_range</span> R, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O,<br /></span>
<p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; std<span class="sy4">::</span><span class="me2">indirect_unary_predicate</span><span class="sy1">&lt;</span>std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1">&lt;</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1">&lt;</span>R<span class="sy1">&gt;</span>, Proj<span class="sy1">&gt;&gt;</span> Pred <span class="sy1">&gt;</span><br />
requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1">&lt;</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1">&lt;</span>R<span class="sy1">&gt;</span>, O<span class="sy1">&gt;</span><br />
&nbsp; <span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">copy_if_result</span><span class="sy1">&lt;</span>ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1">&lt;</span>R<span class="sy1">&gt;</span>, O<span class="sy1">&gt;</span><br /></p>
copy_if<span class="br0">(</span> R<span class="sy3">&amp;&amp;</span> r, O result, Pred pred, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(4)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<div>&#36741;&#21161;&#31867;&#22411;</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> I, <span class="kw1">class</span> O <span class="sy1">&gt;</span><br />
<span class="kw1">using</span> copy_result <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">in_out_result</span><span class="sy1">&lt;</span>I, O<span class="sy1">&gt;</span><span class="sy4">;</span></span></div>
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<td>(5)</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> I, <span class="kw1">class</span> O <span class="sy1">&gt;</span><br />
<span class="kw1">using</span> copy_if_result <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">in_out_result</span><span class="sy1">&lt;</span>I, O<span class="sy1">&gt;</span><span class="sy4">;</span></span></div>
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<td>(6)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<p>&#22797;&#21046; <code>[first, last)</code> &#25152;&#23450;&#20041;&#30340;&#33539;&#22260;&#20013;&#30340;&#20803;&#32032;&#21040;&#22987;&#20110; <code>result</code> &#30340;&#21478;&#19968;&#33539;&#22260;&#12290;</p>
<div class="t-li1"><span class="t-li">1)</span> &#22797;&#21046;&#22987;&#20110; <code>first</code> &#24182;&#25345;&#32493;&#21040; <code>last</code> - 1 &#30340;&#33539;&#22260; <code>[first, last)</code> &#20013;&#30340;&#20803;&#32032;&#12290;&#33509; <code>result</code> &#22312;&#33539;&#22260; <code>[first, last)</code> &#20869;&#21017;&#34892;&#20026;&#26410;&#23450;&#20041;&#12290;&#27492;&#24773;&#20917;&#19979;&#65292;&#21487;&#29992; <span class="t-lc">ranges::copy_backward</span> &#20195;&#26367;&#12290;</div>
<div class="t-li1"><span class="t-li">3)</span> &#20165;&#22797;&#21046;&#35859;&#35789; <code>pred</code> &#23545;&#20854;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#30340;&#20803;&#32032;&#12290;&#20445;&#25345;&#22797;&#21046;&#30340;&#20803;&#32032;&#39034;&#24207;&#12290;&#33509;&#28304;&#19982;&#30446;&#26631;&#33539;&#22260;&#37325;&#21472;&#21017;&#34892;&#20026;&#26410;&#23450;&#20041;&#12290;</div>
<div class="t-li1"><span class="t-li">2,4)</span> &#21516; <span class="t-v">(1,3)</span> &#65292;&#20294;&#20197; <code>r</code> &#20026;&#28304;&#33539;&#22260;&#65292;&#22914;&#21516;&#20197; <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r<span class="br0">)</span></span></span> &#20026; <code>first</code> &#24182;&#20197; <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r<span class="br0">)</span></span></span> &#20026; <code>last</code> &#12290;</div>
<p>&#27492;&#39029;&#38754;&#19978;&#25551;&#36848;&#30340;&#20223;&#20989;&#25968;&#23454;&#20307;&#26159; <i>niebloid</i> &#65292;&#21363;&#65306;</p>
<ul>
<li>&#35843;&#29992;&#23427;&#20204;&#20013;&#30340;&#20219;&#20309;&#19968;&#32773;&#26102;&#19981;&#21487;&#25351;&#23450;&#26174;&#24335;&#27169;&#26495;&#23454;&#21442;&#12290;</li>
<li>&#23427;&#20204;&#26080;&#19968;&#23545;<a href="cpp-language-adl.html">&#23454;&#21442;&#20381;&#36182;&#26597;&#25214;</a>&#21487;&#35265;&#12290;</li>
<li>&#22312;<a href="cpp-language-unqualified_lookup.html">&#36890;&#24120;&#26080;&#38480;&#23450;&#26597;&#25214;</a>&#23547;&#25214;&#20989;&#25968;&#35843;&#29992;&#36816;&#31639;&#31526;&#24038;&#20391;&#30340;&#21517;&#31216;&#25214;&#21040;&#23427;&#20204;&#20043;&#19968;&#26102;&#65292;&#23427;&#31105;&#27490;<a href="cpp-language-adl.html">&#23454;&#21442;&#20381;&#36182;&#26597;&#25214;</a>&#12290;</li>
</ul>
<p>&#23454;&#38469;&#19978;&#65292;&#23427;&#20204;&#33021;&#20197;&#20989;&#25968;&#23545;&#35937;&#65292;&#25110;&#20197;&#26576;&#20123;&#29305;&#27530;&#32534;&#35793;&#22120;&#25193;&#23637;&#23454;&#29616;&#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
<table class="t-par-begin">
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<td>first, last</td>
<td>-</td>
<td>&#35201;&#22797;&#21046;&#30340;&#20803;&#32032;&#33539;&#22260;</td>
</tr>
<tr class="t-par">
<td>r</td>
<td>-</td>
<td>&#35201;&#22797;&#21046;&#30340;&#20803;&#32032;&#33539;&#22260;</td>
</tr>
<tr class="t-par">
<td>result</td>
<td>-</td>
<td>&#30446;&#26631;&#33539;&#22260;&#30340;&#36215;&#22987;</td>
</tr>
<tr class="t-par">
<td>pred</td>
<td>-</td>
<td>&#24212;&#29992;&#21040;&#25237;&#24433;&#21518;&#20803;&#32032;&#30340;&#35859;&#35789;</td>
</tr>
<tr class="t-par">
<td>proj</td>
<td>-</td>
<td>&#24212;&#29992;&#21040;&#20803;&#32032;&#30340;&#25237;&#24433;</td>
</tr>
</table>
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#21547;&#26377;&#31561;&#20110; <code>last</code> &#30340;&#36755;&#20837;&#36845;&#20195;&#22120;&#21644;&#25351;&#21521;&#26368;&#21518;&#22797;&#21046;&#20803;&#32032;&#21518;&#19968;&#20301;&#32622;&#30340;&#36755;&#20986;&#36845;&#20195;&#22120;&#30340; <span class="t-lc">ranges::in_out_result</span> &#12290;</p>
<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">&#22797;&#26434;&#24230;</span></h3>
<div class="t-li1"><span class="t-li">1-2)</span> &#20934;&#30830;&#36171;&#20540; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span>last <span class="sy2">-</span> first<span class="br0">)</span></span></span> &#27425;&#12290;</div>
<div class="t-li1"><span class="t-li">3-4)</span> &#20934;&#30830;&#24212;&#29992; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span>last <span class="sy2">-</span> first<span class="br0">)</span></span></span> &#27425;&#35859;&#35789;&#19982;&#25237;&#24433;&#65292;&#24182;&#36171;&#20540; <span class="t-c"><span class="mw-geshi cpp source-cpp">&#8203;<span class="nu0">0</span>&#8203;</span></span> &#21040; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span>last <span class="sy2">-</span> first<span class="br0">)</span></span></span> &#20043;&#38388;&#27425;&#65288;&#23545;&#27599;&#20010;&#35859;&#35789;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#30340;&#20803;&#32032;&#36171;&#20540;&#65292;&#21462;&#20915;&#20110;&#35859;&#35789;&#19982;&#36755;&#20837;&#25968;&#25454;&#65289;&#12290;</div>
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<p>&#23454;&#36341;&#20013;&#65292; <code>std::ranges::copy</code> &#30340;&#23454;&#29616;&#33509;&#20540;&#31867;&#22411;&#20026;<a href="cpp-named_req-TriviallyCopyable.html"><span style="font-style:italic">&#21487;&#24179;&#20961;&#22797;&#21046;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(TriviallyCopyable)</span></a> &#19988;&#36845;&#20195;&#22120;&#31867;&#22411;&#28385;&#36275; <a href="cpp-iterator-contiguous_iterator.html"><code>contiguous_iterator</code></a> &#65292;&#21017;&#36991;&#20813;&#22810;&#27425;&#36171;&#20540;&#24182;&#20351;&#29992;&#22914; <span class="t-lc"><a href="cpp-string-byte-memmove.html">std::memmove</a></span> &#30340;&#22823;&#22359;&#22797;&#21046;&#20989;&#25968;&#12290;</p>
<p>&#22797;&#21046;&#37325;&#21472;&#30340;&#33539;&#22260;&#26102;&#65292; <code>std::ranges::copy</code> &#22312;&#21521;&#24038;&#22797;&#21046;&#65288;&#30446;&#26631;&#33539;&#22260;&#30340;&#36215;&#22987;&#22312;&#28304;&#33539;&#22260;&#22806;&#65289;&#26102;&#36866;&#21512;&#65292;&#32780; <span class="t-lc">std::ranges::copy_backward</span> &#22312;&#21521;&#21491;&#22797;&#21046;&#65288;&#30446;&#26631;&#33539;&#22260;&#30340;&#26411;&#23614;&#22312;&#28304;&#33539;&#22260;&#22806;&#65289;&#26102;&#36866;&#21512;&#12290;</p>
<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">struct</span> copy_fn <span class="br0">{</span>
<span class="kw1">template</span><span class="sy1">&lt;</span> std<span class="sy4">::</span><span class="me2">input_iterator</span> I, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1">&lt;</span>I<span class="sy1">&gt;</span> S, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O <span class="sy1">&gt;</span>
requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1">&lt;</span>I, O<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">copy_result</span><span class="sy1">&lt;</span>I, O<span class="sy1">&gt;</span> operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span> I first, S last, O result <span class="br0">)</span> <span class="kw4">const</span>
<span class="br0">{</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="sy4">;</span> first <span class="sy3">!</span><span class="sy1">=</span> last<span class="sy4">;</span> <span class="sy2">++</span>first, <span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span><span class="sy2">++</span>result<span class="br0">)</span> <span class="br0">{</span>
<span class="sy2">*</span>result <span class="sy1">=</span> <span class="sy2">*</span>first<span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">return</span> <span class="br0">{</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>first<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>result<span class="br0">)</span><span class="br0">}</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">template</span><span class="sy1">&lt;</span> ranges<span class="sy4">::</span><span class="me2">input_range</span> R, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O <span class="sy1">&gt;</span>
requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1">&lt;</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1">&lt;</span>R<span class="sy1">&gt;</span>, O<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">copy_result</span><span class="sy1">&lt;</span>ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1">&lt;</span>R<span class="sy1">&gt;</span>, O<span class="sy1">&gt;</span>
operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span> R<span class="sy3">&amp;&amp;</span> r, O result <span class="br0">)</span> <span class="kw4">const</span>
<span class="br0">{</span>
<span class="kw1">return</span> <span class="br0">(</span><span class="sy2">*</span>this<span class="br0">)</span><span class="br0">(</span>ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r<span class="br0">)</span>, ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>result<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span>
<span class="kw1">inline</span> <span class="kw4">constexpr</span> copy_fn copy<span class="sy4">;</span></pre></div>
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<th>&#29256;&#26412;&#20108;</th>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="cpp source-cpp">
<pre class="de1"><span class="kw1">struct</span> copy_if_fn <span class="br0">{</span>
<span class="kw1">template</span><span class="sy1">&lt;</span> std<span class="sy4">::</span><span class="me2">input_iterator</span> I, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1">&lt;</span>I<span class="sy1">&gt;</span> S, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O,
<span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,
std<span class="sy4">::</span><span class="me2">indirect_unary_predicate</span><span class="sy1">&lt;</span>std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1">&lt;</span>I, Proj<span class="sy1">&gt;&gt;</span> Pred <span class="sy1">&gt;</span>
requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1">&lt;</span>I, O<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">copy_if_result</span><span class="sy1">&lt;</span>I, O<span class="sy1">&gt;</span>
operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span> I first, S last, O result, Pred pred, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span> <span class="kw4">const</span>
<span class="br0">{</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="sy4">;</span> first <span class="sy3">!</span><span class="sy1">=</span> last<span class="sy4">;</span> <span class="sy2">++</span>first<span class="br0">)</span> <span class="br0">{</span>
<span class="kw1">if</span> <span class="br0">(</span><a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>pred, <a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>proj, <span class="sy2">*</span>first<span class="br0">)</span><span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
<span class="sy2">*</span>result <span class="sy1">=</span> <span class="sy2">*</span>first<span class="sy4">;</span>
<span class="sy2">++</span>result<span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span>
<span class="kw1">return</span> <span class="br0">{</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>first<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>result<span class="br0">)</span><span class="br0">}</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">template</span><span class="sy1">&lt;</span> ranges<span class="sy4">::</span><span class="me2">input_range</span> R, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O,
<span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,
std<span class="sy4">::</span><span class="me2">indirect_unary_predicate</span><span class="sy1">&lt;</span>
std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1">&lt;</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1">&lt;</span>R<span class="sy1">&gt;</span>, Proj<span class="sy1">&gt;&gt;</span> Pred <span class="sy1">&gt;</span>
requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1">&lt;</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1">&lt;</span>R<span class="sy1">&gt;</span>, O<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">copy_if_result</span><span class="sy1">&lt;</span>ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1">&lt;</span>R<span class="sy1">&gt;</span>, O<span class="sy1">&gt;</span>
operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span> R<span class="sy3">&amp;&amp;</span> r, O result, Pred pred, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span> <span class="kw4">const</span>
<span class="br0">{</span>
<span class="kw1">return</span> <span class="br0">(</span><span class="sy2">*</span>this<span class="br0">)</span><span class="br0">(</span>ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r<span class="br0">)</span>, ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r<span class="br0">)</span>,
std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>result<span class="br0">)</span>,
<a href="cpp-utility-functional-ref.html"><span class="kw1069">std::<span class="me2">ref</span></span></a><span class="br0">(</span>pred<span class="br0">)</span>, <a href="cpp-utility-functional-ref.html"><span class="kw1069">std::<span class="me2">ref</span></span></a><span class="br0">(</span>proj<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span>
<span class="kw1">inline</span> <span class="kw4">constexpr</span> copy_if_fn copy_if<span class="sy4">;</span></pre></div>
</div>
</td>
</tr>
</table>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
<div class="t-example">
<p>&#19979;&#21015;&#20195;&#30721;&#29992; <code>copy</code> &#22797;&#21046; <code>vector</code> &#30340;&#20869;&#23481;&#21040;&#21478;&#19968; <code>vector</code> &#24182;&#26174;&#31034;&#32467;&#26524; <code>vector</code> &#65306;</p>
<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;algorithm&gt;</span>
<span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;vector&gt;</span>
<span class="co2">#include &lt;iterator&gt;</span>
<span class="co2">#include &lt;numeric&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> from_vector<span class="br0">(</span><span class="nu0">10</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-algorithm-iota.html"><span class="kw1655">std::<span class="me2">iota</span></span></a><span class="br0">(</span>from_vector.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, from_vector.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>, <span class="nu0">0</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> to_vector<span class="sy4">;</span>
<span class="kw1">namespace</span> ranges <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">;</span>
ranges<span class="sy4">::</span><span class="me2">copy</span><span class="br0">(</span>from_vector.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, from_vector.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>,
<a href="cpp-iterator-back_inserter.html"><span class="kw665">std::<span class="me2">back_inserter</span></span></a><span class="br0">(</span>to_vector<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<span class="co1">// &#25110;&#32773;&#21478;&#22806;&#20351;&#29992;</span>
<span class="co1">// std::vector&lt;int&gt; to_vector(from_vector.size());</span>
<span class="co1">// ranges::copy(from_vector.begin(), from_vector.end(), to_vector.begin());</span>
<span class="co1">// &#37117;&#31561;&#20215;&#20110;</span>
<span class="co1">// std::vector&lt;int&gt; to_vector = from_vector;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;to_vector contains: &quot;</span><span class="sy4">;</span>
ranges<span class="sy4">::</span><span class="me2">copy</span><span class="br0">(</span>to_vector, <a href="cpp-iterator-ostream_iterator.html"><span class="kw670">std::<span class="me2">ostream_iterator</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span><span class="br0">(</span><a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>, <span class="st0">&quot; &quot;</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;odd numbers in to_vector are: &quot;</span><span class="sy4">;</span>
ranges<span class="sy4">::</span><span class="me2">copy_if</span><span class="br0">(</span>to_vector, <a href="cpp-iterator-ostream_iterator.html"><span class="kw670">std::<span class="me2">ostream_iterator</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span><span class="br0">(</span><a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>, <span class="st0">&quot; &quot;</span><span class="br0">)</span>,
<span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">int</span> x<span class="br0">)</span> <span class="br0">{</span> <span class="kw1">return</span> <span class="br0">(</span>x <span class="sy2">%</span> <span class="nu0">2</span><span class="br0">)</span> <span class="sy1">==</span> <span class="nu0">1</span><span class="sy4">;</span> <span class="br0">}</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
</div>
<p>&#36755;&#20986;&#65306;</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="text source-text">
<pre class="de1">to_vector contains: 0 1 2 3 4 5 6 7 8 9
odd numbers in to_vector are: 1 3 5 7 9</pre></div>
</div>
</div>
<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-algorithm-ranges-copy_backward.html"><span class="t-lines"><span>ranges::copy_backward</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
</div>
</td>
<td>&#25353;&#20174;&#21518;&#24448;&#21069;&#30340;&#39034;&#24207;&#22797;&#21046;&#19968;&#20010;&#33539;&#22260;&#20869;&#30340;&#20803;&#32032;<br />
<span class="t-mark">(niebloid)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-ranges-reverse_copy.html"><span class="t-lines"><span>ranges::revserse_copy</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
</div>
</td>
<td>&#21019;&#24314;&#19968;&#20010;&#33539;&#22260;&#30340;&#36870;&#21521;&#21103;&#26412;<br />
<span class="t-mark">(niebloid)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-ranges-copy_n.html"><span class="t-lines"><span>ranges::copy_n</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
</div>
</td>
<td>&#23558;&#19968;&#23450;&#25968;&#30446;&#30340;&#20803;&#32032;&#22797;&#21046;&#21040;&#19968;&#20010;&#26032;&#30340;&#20301;&#32622;<br />
<span class="t-mark">(niebloid)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-ranges-fill.html"><span class="t-lines"><span>ranges::fill</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
</div>
</td>
<td>&#23558;&#19968;&#20010;&#32473;&#23450;&#20540;&#22797;&#21046;&#36171;&#20540;&#32473;&#19968;&#20010;&#33539;&#22260;&#20869;&#30340;&#27599;&#20010;&#20803;&#32032;<br />
<span class="t-mark">(niebloid)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-ranges-remove_copy.html"><span class="t-lines"><span>ranges::remove_copy</span><span>ranges::remove_copy_if</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
</div>
</td>
<td>&#22797;&#21046;&#19968;&#20010;&#33539;&#22260;&#30340;&#20803;&#32032;&#65292;&#24573;&#30053;&#28385;&#36275;&#29305;&#23450;&#21028;&#21035;&#26631;&#20934;&#30340;&#20803;&#32032;<br />
<span class="t-mark">(niebloid)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-copy.html"><span class="t-lines"><span>copy</span><span>copy_if</span></span></a></div>
<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
</div>
</td>
<td>&#23558;&#26576;&#19968;&#33539;&#22260;&#30340;&#20803;&#32032;&#22797;&#21046;&#21040;&#19968;&#20010;&#26032;&#30340;&#20301;&#32622;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
</tr>
</table>
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<div class="visualClear"></div>
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