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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::allocator&lt;T&gt;::</span>deallocate</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-memory.html">memory</a>&lrm; | <a href="cpp-memory-allocator.html">allocator</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> deallocate<span class="br0">(</span> T<span class="sy2">*</span> p, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> n <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><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> deallocate<span class="br0">(</span> T<span class="sy2">*</span> p, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> n <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>&#20174;&#25351;&#38024; <code>p</code> &#25152;&#24341;&#29992;&#30340;&#23384;&#20648;&#35299;&#20998;&#37197;&#65292;&#25351;&#38024;&#24517;&#39035;&#26159;&#36890;&#36807;&#20808;&#21069;&#35843;&#29992; <span class="t-lc"><a href="cpp-memory-allocator-allocate.html">allocate()</a></span> <span class="t-rev-inl t-since-cxx23"><span>&#25110; <a href="cpp-memory-allocator-allocate_at_least.html"><code>allocate_at_least()</code></a></span> <span><span class="t-mark-rev t-since-cxx23">(C++23 &#36215;)</span></span></span> &#33719;&#24471;&#30340;&#25351;&#38024;&#12290;</p>
<p>&#21442;&#25968; <code>n</code> &#24517;&#39035;&#31561;&#20110;&#23545;&#21407;&#20808;&#29983;&#25104; <code>p</code> &#30340; <span class="t-lc"><a href="cpp-memory-allocator-allocate.html">allocate()</a></span> &#35843;&#29992;&#30340;&#39318;&#21442;&#25968;<span class="t-rev-inl t-since-cxx23"><span>&#65292;&#25110;&#33509; <code>p</code> &#30001;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">{</span>p, count<span class="br0">}</span></span></span> &#30340;&#35843;&#29992; <span class="t-c"><span class="mw-geshi cpp source-cpp">allocate_at_least<span class="br0">(</span>m<span class="br0">)</span></span></span> &#33719;&#24471;&#65292;&#21017;&#22312;&#33539;&#22260; <code>[m, count]</code> &#20013;</span> <span><span class="t-mark-rev t-since-cxx23">(C++23 &#36215;)</span></span></span>&#65307;&#21542;&#21017;&#34892;&#20026;&#26410;&#23450;&#20041;&#12290;</p>
<p>&#35843;&#29992; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy4">::</span><a href="cpp-memory-new-operator_delete.html"><span class="kw689">operator delete</span></a><span class="br0">(</span><span class="kw4">void</span><span class="sy2">*</span><span class="br0">)</span></span></span> <span class="t-rev-inl t-since-cxx17"><span>&#25110; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy4">::</span><a href="cpp-memory-new-operator_delete.html"><span class="kw689">operator delete</span></a><span class="br0">(</span><span class="kw4">void</span><span class="sy2">*</span>, <a href="cpp-memory-new-align_val_t.html"><span class="kw697">std::<span class="me2">align_val_t</span></span></a><span class="br0">)</span></span></span></span> <span><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></span></span>&#65292;&#20294;&#20309;&#26102;&#21450;&#22914;&#20309;&#35843;&#29992;&#26159;&#26410;&#25351;&#23450;&#30340;&#12290;</p>
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<p>&#22312;&#24120;&#37327;&#34920;&#36798;&#24335;&#30340;&#27714;&#20540;&#20013;&#65292;&#27492;&#20989;&#25968;&#24517;&#39035;&#35299;&#20998;&#37197;&#22312;&#21516;&#19968;&#34920;&#36798;&#24335;&#30340;&#27714;&#20540;&#20869;&#20998;&#37197;&#30340;&#23384;&#20648;&#12290;</p>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>&#20174; <code>allocate()</code> <span class="t-rev-inl t-since-cxx23"><span>&#25110; <a href="cpp-memory-allocator-allocate_at_least.html"><code>allocate_at_least()</code></a></span> <span><span class="t-mark-rev t-since-cxx23">(C++23 &#36215;)</span></span></span> &#33719;&#24471;&#30340;&#25351;&#38024;</td>
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<td>&#20808;&#21069;&#20256;&#36882;&#32473; <code>allocate()</code> &#30340;&#23545;&#35937;&#25968;<span class="t-rev-inl t-since-cxx23"><span>&#65292;&#25110;&#22312;&#32463;&#30001; <a href="cpp-memory-allocator-allocate_at_least.html"><code>allocate_at_least()</code></a> &#35831;&#27714;&#21644;&#23454;&#38469;&#20998;&#37197;&#30340;&#23545;&#35937;&#25968;&#20043;&#38388;&#30340;&#25968;&#65288;&#21487;&#20197;&#31561;&#20110;&#20219;&#19968;&#36793;&#30028;&#65289;</span> <span><span class="t-mark-rev t-since-cxx23">(C++23 &#36215;)</span></span></span></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=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
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<pre class="de1"><span class="co2">#include &lt;algorithm&gt;</span>
<span class="co2">#include &lt;cstddef&gt;</span>
<span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;memory&gt;</span>
<span class="co2">#include &lt;string&gt;</span>
<span class="kw1">class</span> S <span class="br0">{</span>
<span class="kw1">inline</span> <span class="kw4">static</span> <span class="kw4">int</span> n<span class="br0">{</span><span class="nu0">1</span><span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">int</span> m<span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">void</span> pre<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</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> <span class="st0">&quot;#&quot;</span> <span class="sy1">&lt;&lt;</span> m <span class="sy1">&lt;&lt;</span> <a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a><span class="br0">(</span>m, <span class="st0">&#39; &#39;</span><span class="br0">)</span><span class="sy4">;</span> <span class="br0">}</span>
<span class="kw1">public</span><span class="sy4">:</span>
S<span class="br0">(</span><span class="kw4">int</span> x<span class="br0">)</span> <span class="sy4">:</span> m<span class="br0">{</span>n<span class="sy2">++</span><span class="br0">}</span> <span class="br0">{</span> pre<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;S::S(&quot;</span> <span class="sy1">&lt;&lt;</span> x <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>
~S<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span> pre<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;S::~S();<span class="es1">\n</span>&quot;</span><span class="sy4">;</span> <span class="br0">}</span>
<span class="kw4">void</span> id<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span> pre<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;S::id();<span class="es1">\n</span>&quot;</span><span class="sy4">;</span> <span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span>
<span class="kw4">constexpr</span> <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> n<span class="br0">{</span><span class="nu0">4</span><span class="br0">}</span><span class="sy4">;</span>
<a href="cpp-memory-allocator.html"><span class="kw700">std::<span class="me2">allocator</span></span></a><span class="sy1">&lt;</span>S<span class="sy1">&gt;</span> allocator<span class="sy4">;</span>
<span class="kw1">try</span> <span class="br0">{</span>
S<span class="sy2">*</span> s <span class="sy1">=</span> allocator.<span class="me1">allocate</span><span class="br0">(</span>n<span class="br0">)</span><span class="sy4">;</span> <span class="co1">// &#21487;&#33021;&#25243;&#20986;</span>
<span class="kw1">for</span> <span class="br0">(</span><a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> i<span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span> i <span class="sy3">!</span><span class="sy1">=</span> n<span class="sy4">;</span> <span class="sy2">++</span>i<span class="br0">)</span> <span class="br0">{</span>
<span class="co1">// allocator.construct(&amp;s[i], i+42); // C++20 &#20013;&#31227;&#38500;</span>
std<span class="sy4">::</span><span class="me2">construct_at</span><span class="br0">(</span><span class="sy3">&amp;</span>s<span class="br0">[</span>i<span class="br0">]</span>, i<span class="sy2">+</span><span class="nu0">42</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// C++20 &#36215;</span>
<span class="br0">}</span>
<a href="cpp-algorithm-for_each_n.html"><span class="kw1569">std::<span class="me2">for_each_n</span></span></a><span class="br0">(</span>s, n, <span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">const</span> <span class="kw4">auto</span><span class="sy3">&amp;</span> e<span class="br0">)</span> <span class="br0">{</span> e.<span class="me1">id</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span> <span class="br0">}</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-memory-destroy_n.html"><span class="kw729">std::<span class="me2">destroy_n</span></span></a><span class="br0">(</span>s, n<span class="br0">)</span><span class="sy4">;</span>
allocator.<span class="me1">deallocate</span><span class="br0">(</span>s, n<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">catch</span><span class="br0">(</span><a href="cpp-memory-new-bad_array_new_length.html"><span class="kw694">std::<span class="me2">bad_array_new_length</span></span></a> <span class="kw4">const</span><span class="sy3">&amp;</span> ex<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> ex.<span class="me1">what</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>
<span class="kw1">catch</span><span class="br0">(</span><a href="cpp-memory-new-bad_alloc.html"><span class="kw693">std::<span class="me2">bad_alloc</span></span></a> <span class="kw4">const</span><span class="sy3">&amp;</span> ex<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> ex.<span class="me1">what</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>
<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">#1 S::S(42);
#2 S::S(43);
#3 S::S(44);
#4 S::S(45);
#1 S::id();
#2 S::id();
#3 S::id();
#4 S::id();
#1 S::~S();
#2 S::~S();
#3 S::~S();
#4 S::~S();</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-memory-allocator-allocate.html"><span class="t-lines"><span>allocate</span></span></a></div>
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<td>&#20998;&#37197;&#26410;&#21021;&#22987;&#21270;&#30340;&#23384;&#20648;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<td>
<div class="t-dsc-member-div">
<div><a href="cpp-memory-allocator-allocate_at_least.html"><span class="t-lines"><span>allocate_at_least</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx23">(C++23)</span></span></span></div>
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</td>
<td>&#20998;&#37197;&#19982;&#35831;&#27714;&#30340;&#22823;&#23567;&#33267;&#23569;&#19968;&#26679;&#22823;&#30340;&#26410;&#21021;&#22987;&#21270;&#23384;&#20648;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div class="t-dsc-member-div">
<div><a href="cpp-memory-allocator_traits-deallocate.html"><span class="t-lines"><span>deallocate</span></span></a></div>
<div><span class="t-lines"><span><span class="t-cmark">[&#38745;&#24577;]</span></span></span></div>
</div>
</td>
<td>&#29992;&#20998;&#37197;&#22120;&#35299;&#20998;&#37197;&#23384;&#20648;<br />
<span class="t-mark">(<code>std::allocator_traits&lt;Alloc&gt;</code> &#30340;&#20844;&#24320;&#38745;&#24577;&#25104;&#21592;&#20989;&#25968;)</span></td>
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