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<title>std::ranges::subrange&lt;I,S,K&gt;::begin</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::ranges::subrange&lt;I,S,K&gt;::</span>begin</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-ranges.html">ranges</a>&lrm; | <a href="cpp-ranges-subrange.html">subrange</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> I begin<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> requires std<span class="sy4">::</span><span class="me2">copyable</span><span class="sy1">&lt;</span>I<span class="sy1">&gt;</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="br0">[</span><span class="br0">[</span>nodiscard<span class="br0">]</span><span class="br0">]</span> <span class="kw4">constexpr</span> I begin<span class="br0">(</span><span class="br0">)</span> requires <span class="br0">(</span><span class="sy3">!</span>std<span class="sy4">::</span><span class="me2">copyable</span><span class="sy1">&lt;</span>I<span class="sy1">&gt;</span><span class="br0">)</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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<p>&#33719;&#24471;&#25351;&#21521; <code>subrange</code> &#39318;&#20803;&#32032;&#30340;&#36845;&#20195;&#22120;&#65292;&#25110;&#33509;&#35270;&#22270;&#20026;&#31354;&#21017;&#20026;&#23614;&#36845;&#20195;&#22120;&#12290;</p>
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<div class="t-li1"><span class="t-li">1)</span> &#33509;&#36845;&#20195;&#22120;&#31867;&#22411;&#21487;&#22797;&#21046;&#65292;&#21017;&#36820;&#22238;&#23384;&#20648;&#30340;&#36845;&#20195;&#22120;&#30340;&#21103;&#26412;&#12290;</div>
<div class="t-li1"><span class="t-li">2)</span> &#33509;&#36845;&#20195;&#22120;&#31867;&#22411;&#19981;&#21487;&#22797;&#21046;&#65292;&#21017;&#36820;&#22238;&#20174;&#23384;&#20648;&#30340;&#36845;&#20195;&#22120;&#31227;&#21160;&#26500;&#36896;&#30340;&#36845;&#20195;&#22120;&#12290;</div>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
<p>&#65288;&#26080;&#65289;</p>
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<div class="t-li1"><span class="t-li">1)</span> &#20174;&#23384;&#20648;&#30340;&#36845;&#20195;&#22120;&#22797;&#21046;&#26500;&#36896;&#30340;&#36845;&#20195;&#22120;&#12290;</div>
<div class="t-li1"><span class="t-li">2)</span> &#20174;&#23384;&#20648;&#30340;&#36845;&#20195;&#22120;&#31227;&#21160;&#26500;&#36896;&#30340;&#36845;&#20195;&#22120;&#12290;</div>
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<p>&#35843;&#29992; <span class="t-v">(2)</span> &#21487;&#33021;&#23558;&#23384;&#20648;&#30340;&#36845;&#20195;&#22120;&#32622;&#20110;&#21512;&#27861;&#20294;&#26410;&#25351;&#23450;&#30340;&#29366;&#24577;&#65292;&#21462;&#20915;&#20110; <code>I</code> &#30340;&#26500;&#36896;&#20989;&#25968;&#30340;&#34892;&#20026;&#12290;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
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<td class="mbox-text" style="">&#26412;&#33410;&#26410;&#23436;&#25104;<br />
&#21407;&#22240;&#65306;&#26242;&#26080;&#31034;&#20363;</td>
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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-ranges-subrange-end.html"><span class="t-lines"><span>end</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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<td>&#33719;&#24471;&#21736;&#20301;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div><a href="cpp-iterator-begin.html"><span class="t-lines"><span>begin</span><span>cbegin</span></span></a></div>
<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-cxx14">(C++14)</span></span></span></div>
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<td>&#36820;&#22238;&#25351;&#21521;&#23481;&#22120;&#25110;&#25968;&#32452;&#36215;&#22987;&#30340;&#36845;&#20195;&#22120;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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<div><a href="cpp-ranges-begin.html"><span class="t-lines"><span>ranges::begin</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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<td>&#36820;&#22238;&#25351;&#21521;&#33539;&#22260;&#36215;&#22987;&#30340;&#36845;&#20195;&#22120;<br />
<span class="t-mark">(&#23450;&#21046;&#28857;&#23545;&#35937;)</span></td>
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