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<title>std::basic_string&lt;CharT,Traits,Allocator&gt;::shrink_to_fit</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::basic_string&lt;CharT,Traits,Allocator&gt;::</span>shrink_to_fit</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-string.html">string</a>&lrm; | <a href="cpp-string-basic_string.html">basic string</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> shrink_to_fit<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-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> shrink_to_fit<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-since-cxx20">(C++20 &#36215;)</span></td>
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<p>&#35831;&#27714;&#31227;&#38500;&#26410;&#20351;&#29992;&#30340;&#23481;&#37327;&#12290;</p>
<p>&#36825;&#26159;&#20943;&#23569; <span class="t-lc"><a href="cpp-string-basic_string-capacity.html">capacity()</a></span> &#21040; <span class="t-lc"><a href="cpp-string-basic_string-size.html">size()</a></span> &#30340;&#38750;&#24378;&#21046;&#35831;&#27714;&#12290;&#26159;&#21542;&#28385;&#36275;&#35831;&#27714;&#21462;&#20381;&#36182;&#20110;&#23454;&#29616;&#12290;</p>
<p>&#33509;&#65288;&#19988;&#21807;&#33509;&#65289;&#21457;&#29983;&#37325;&#20998;&#37197;&#65292;&#21017;&#38750;&#27861;&#21270;&#25152;&#26377;&#25351;&#38024;&#12289;&#24341;&#29992;&#21644;&#36845;&#20195;&#22120;&#12290;</p>
<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>
<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>
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<p>&#65288;&#26410;&#25351;&#26126;&#65289;</p>
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<td><span class="t-mark-rev t-until-cxx17">(C++17 &#21069;)</span></td>
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<p>&#19982; string &#22823;&#23567;&#25104;&#32447;&#24615;</p>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
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<pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;string&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> s<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;Default-constructed capacity is &quot;</span> <span class="sy1">&lt;&lt;</span> s.<span class="me1">capacity</span><span class="br0">(</span><span class="br0">)</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; and size is &quot;</span> <span class="sy1">&lt;&lt;</span> s.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> i<span class="sy1">=</span><span class="nu0">0</span><span class="sy4">;</span> i<span class="sy1">&lt;</span><span class="nu0">42</span><span class="sy4">;</span> i<span class="sy2">++</span><span class="br0">)</span>
s.<span class="me1">append</span><span class="br0">(</span><span class="st0">&quot; 42 &quot;</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;Capacity after a couple of appends is &quot;</span> <span class="sy1">&lt;&lt;</span> s.<span class="me1">capacity</span><span class="br0">(</span><span class="br0">)</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; and size is &quot;</span> <span class="sy1">&lt;&lt;</span> s.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
s.<span class="me1">clear</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">&quot;Capacity after clear() is &quot;</span> <span class="sy1">&lt;&lt;</span> s.<span class="me1">capacity</span><span class="br0">(</span><span class="br0">)</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; and size is &quot;</span> <span class="sy1">&lt;&lt;</span> s.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
s.<span class="me1">shrink_to_fit</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">&quot;Capacity after shrink_to_fit() is &quot;</span> <span class="sy1">&lt;&lt;</span> s.<span class="me1">capacity</span><span class="br0">(</span><span class="br0">)</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; and size is &quot;</span> <span class="sy1">&lt;&lt;</span> s.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <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>&#21487;&#33021;&#30340;&#36755;&#20986;&#65306;</p>
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<pre class="de1">Default-constructed capacity is 15 and size 0
Capacity after a couple of appends is 240 and size 168
Capacity after clear() is 240 and size 0
Capacity after shrink_to_fit() is 15 and size 0</pre></div>
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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-string-basic_string-size.html"><span class="t-lines"><span>size</span><span>length</span></span></a></div>
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<td>&#36820;&#22238;&#23383;&#31526;&#25968;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div><a href="cpp-string-basic_string-capacity.html"><span class="t-lines"><span>capacity</span></span></a></div>
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<td>&#36820;&#22238;&#24403;&#21069;&#23545;&#35937;&#20998;&#37197;&#30340;&#23384;&#20648;&#31354;&#38388;&#33021;&#20445;&#23384;&#30340;&#23383;&#31526;&#25968;&#37327;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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