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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::vector&lt;T,Allocator&gt;::</span>resize</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-container.html">container</a>&lrm; | <a href="cpp-container-vector.html">vector</a></span></div>
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<td rowspan="142">(1)</td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> resize<span class="br0">(</span> size_type count <span class="br0">)</span><span class="sy4">;</span></span></div>
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<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="kw4">constexpr</span> <span class="kw4">void</span> resize<span class="br0">(</span> size_type count <span class="br0">)</span><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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<td rowspan="142">(2)</td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> resize<span class="br0">(</span> size_type count, T value <span class="sy1">=</span> T<span class="br0">(</span><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">void</span> resize<span class="br0">(</span> size_type count, <span class="kw4">const</span> value_type<span class="sy3">&amp;</span> value <span class="br0">)</span><span class="sy4">;</span></span></div>
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<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="kw4">constexpr</span> <span class="kw4">void</span> resize<span class="br0">(</span> size_type count, <span class="kw4">const</span> value_type<span class="sy3">&amp;</span> value <span class="br0">)</span><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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<p>&#37325;&#35774;&#23481;&#22120;&#22823;&#23567;&#20197;&#23481;&#32435; <code>count</code> &#20010;&#20803;&#32032;&#12290;</p>
<p>&#33509;&#24403;&#21069;&#22823;&#23567;&#22823;&#20110; <code>count</code> &#65292;&#21017;&#20943;&#23567;&#23481;&#22120;&#20026;&#20854;&#39318; <code>count</code> &#20010;&#20803;&#32032;&#12290;</p>
<p>&#33509;&#24403;&#21069;&#22823;&#23567;&#23567;&#20110; <code>count</code> &#65292;</p>
<div class="t-li1"><span class="t-li">1)</span> &#21017;&#21518;&#38468;&#39069;&#22806;&#30340;<a href="cpp-named_req-DefaultInsertable.html">&#40664;&#35748;&#25554;&#20837;</a>&#30340;&#20803;&#32032;</div>
<div class="t-li1"><span class="t-li">2)</span> &#21017;&#21518;&#38468;&#39069;&#22806;&#30340; <code>value</code> &#30340;&#21103;&#26412;</div>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>count</td>
<td>-</td>
<td>&#23481;&#22120;&#30340;&#22823;&#23567;</td>
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<td>value</td>
<td>-</td>
<td>&#29992;&#20197;&#21021;&#22987;&#21270;&#26032;&#20803;&#32032;&#30340;&#20540;</td>
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<td colspan="3">&#31867;&#22411;&#35201;&#27714;</td>
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<td colspan="3">-
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&#20026;&#20351;&#29992;&#37325;&#36733; (1) &#65292; <code>T</code> &#24517;&#39035;&#28385;&#36275;<a href="cpp-named_req-MoveInsertable.html"><span style="font-style:italic">&#21487;&#31227;&#21160;&#25554;&#20837;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(MoveInsertable)</span></a> &#21644; <a href="cpp-named_req-DefaultInsertable.html"><span style="font-style:italic">&#21487;&#40664;&#35748;&#25554;&#20837;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(DefaultInsertable)</span></a> &#30340;&#35201;&#27714;&#12290;</td>
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<td colspan="3">-
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&#20026;&#20351;&#29992;&#37325;&#36733; (2) &#65292; <code>T</code> &#24517;&#39035;&#28385;&#36275;<a href="cpp-named_req-CopyInsertable.html"><span style="font-style:italic">&#21487;&#22797;&#21046;&#25554;&#20837;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(CopyInsertable)</span></a> &#30340;&#35201;&#27714;&#12290;</td>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#65288;&#26080;&#65289;</p>
<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">&#22797;&#26434;&#24230;</span></h3>
<p>&#19982;&#24403;&#21069;&#22823;&#23567;&#21644; <code>count</code> &#38388;&#30340;&#24046;&#25104;&#32447;&#24615;&#12290;&#33509;&#23481;&#37327;&#23567;&#20110; <code>count</code> &#21017;&#21487;&#33021;&#26377;&#37325;&#20998;&#37197;&#25152;&#33268;&#30340;&#39069;&#22806;&#22797;&#26434;&#24230;&#12290;</p>
<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">&#24322;&#24120;</span></h3>
<p>&#33509;&#25243;&#20986;&#24322;&#24120;&#65292;&#21017;&#27492;&#20989;&#25968;&#26080;&#25928;&#26524;&#65288;<a href="cpp-language-exceptions.html">&#24378;&#24322;&#24120;&#20445;&#35777;</a>&#65289;&#12290;</p>
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<p>&#37325;&#36733; <span class="t-v">(1)</span> &#20013;&#65292;&#33509; <code>T</code> &#30340;&#31227;&#21160;&#26500;&#36896;&#20989;&#25968;&#19981;&#26159; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">noexcept</span></span></span> &#19988; T &#19981;<a href="cpp-named_req-CopyInsertable.html"><span style="font-style:italic">&#21487;&#22797;&#21046;&#25554;&#20837;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(CopyInsertable)</span></a> &#21040; <code>*this</code> &#65292;&#21017; <code>vector</code> &#23558;&#20351;&#29992;&#20250;&#25243;&#20986;&#30340;&#31227;&#21160;&#26500;&#36896;&#20989;&#25968;&#12290;&#33509;&#23427;&#25243;&#20986;&#65292;&#21017;&#25243;&#24323;&#20445;&#35777;&#19988;&#25928;&#26524;&#26410;&#25351;&#23450;&#12290;</p>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<p>&#33509;&#19981;&#24819;&#35201;&#37325;&#36733; <span class="t-v">(1)</span> &#20013;&#30340;&#20540;&#21021;&#22987;&#21270;&#65292;&#20363;&#22914;&#20803;&#32032;&#26159;&#38750;&#31867;&#31867;&#22411;&#19988;&#19981;&#38656;&#35201;&#28165;&#38646;&#65292;&#21017;&#21487;&#20197;&#25552;&#20379;<a rel="nofollow" class="external text" href="http://stackoverflow.com/a/21028912/273767">&#23450;&#21046;&#30340; <code>Allocator::construct</code></a> &#36991;&#20813;&#12290; &#22312;&#37325;&#35774;&#22823;&#23567;&#21040;&#36739;&#23567;&#20540;&#26102;&#65292; <code>vector</code> &#30340;&#23481;&#37327;&#20915;&#19981;&#20943;&#23569;&#65292;&#22240;&#20026;&#36825;&#20250;&#38750;&#27861;&#21270;&#25152;&#26377;&#30340;&#65292;&#32780;&#38750;&#21482;&#38750;&#27861;&#21270;&#31561;&#20215;&#30340; <a href="cpp-container-vector-pop_back.html"><code>pop_back()</code></a> &#35843;&#29992;&#24207;&#21015;&#25152;&#38750;&#27861;&#21270;&#30340;&#36845;&#20195;&#22120;&#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;iostream&gt;</span>
<span class="co2">#include &lt;vector&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> c <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">3</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">&quot;The vector holds: &quot;</span><span class="sy4">;</span>
<span class="kw1">for</span><span class="br0">(</span><span class="kw4">auto</span><span class="sy3">&amp;</span> el<span class="sy4">:</span> c<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> el <span class="sy1">&lt;&lt;</span> <span class="st0">&#39; &#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">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
c.<span class="me1">resize</span><span class="br0">(</span><span class="nu0">5</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">&quot;After resize up to 5: &quot;</span><span class="sy4">;</span>
<span class="kw1">for</span><span class="br0">(</span><span class="kw4">auto</span><span class="sy3">&amp;</span> el<span class="sy4">:</span> c<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> el <span class="sy1">&lt;&lt;</span> <span class="st0">&#39; &#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">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
c.<span class="me1">resize</span><span class="br0">(</span><span class="nu0">2</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">&quot;After resize down to 2: &quot;</span><span class="sy4">;</span>
<span class="kw1">for</span><span class="br0">(</span><span class="kw4">auto</span><span class="sy3">&amp;</span> el<span class="sy4">:</span> c<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> el <span class="sy1">&lt;&lt;</span> <span class="st0">&#39; &#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">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<p>&#36755;&#20986;&#65306;</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="text source-text">
<pre class="de1">The vector holds: 1 2 3
After resize up to 5: 1 2 3 0 0
After resize down to 2: 1 2</pre></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
<table class="t-dsc-begin">
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<div class="t-dsc-member-div">
<div><a href="cpp-container-vector-size.html"><span class="t-lines"><span>size</span></span></a></div>
</div>
</td>
<td>&#36820;&#22238;&#23481;&#32435;&#30340;&#20803;&#32032;&#25968;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-container-vector-insert.html"><span class="t-lines"><span>insert</span></span></a></div>
</div>
</td>
<td>&#25554;&#20837;&#20803;&#32032;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-container-vector-erase.html"><span class="t-lines"><span>erase</span></span></a></div>
</div>
</td>
<td>&#25830;&#38500;&#20803;&#32032;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div class="visualClear"></div>
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