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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>atomic_fetch_sub, <span style="font-size:0.7em; line-height:130%">std::</span>atomic_fetch_sub_explicit</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-atomic.html">atomic</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-atomic.html">&lt;atomic&gt;</a></code></div>
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<td rowspan="142">(1)</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> T <span class="sy1">&gt;</span><br /></span>
<p>T atomic_fetch_sub<span class="br0">(</span> <a href="cpp-atomic-atomic.html"><span class="kw2066">std::<span class="me2">atomic</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy2">*</span> obj,<br /></p>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <span class="kw1">typename</span> <a href="cpp-atomic-atomic.html"><span class="kw2066">std::<span class="me2">atomic</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">difference_type</span> arg <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></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> T <span class="sy1">&gt;</span><br /></span>
<p>T atomic_fetch_sub<span class="br0">(</span> <span class="kw4">volatile</span> <a href="cpp-atomic-atomic.html"><span class="kw2066">std::<span class="me2">atomic</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy2">*</span> obj,<br /></p>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <span class="kw1">typename</span> <a href="cpp-atomic-atomic.html"><span class="kw2066">std::<span class="me2">atomic</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">difference_type</span> arg <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
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<td rowspan="142">(2)</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> T <span class="sy1">&gt;</span><br /></span>
<p>T atomic_fetch_sub_explicit<span class="br0">(</span> <a href="cpp-atomic-atomic.html"><span class="kw2066">std::<span class="me2">atomic</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy2">*</span> obj,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw1">typename</span> <a href="cpp-atomic-atomic.html"><span class="kw2066">std::<span class="me2">atomic</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">difference_type</span> arg,<br /></p>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<a href="cpp-atomic-memory_order.html"><span class="kw2088">std::<span class="me2">memory_order</span></span></a> order <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></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> T <span class="sy1">&gt;</span><br /></span>
<p>T atomic_fetch_sub_explicit<span class="br0">(</span> <span class="kw4">volatile</span> <a href="cpp-atomic-atomic.html"><span class="kw2066">std::<span class="me2">atomic</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy2">*</span> obj,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw1">typename</span> <a href="cpp-atomic-atomic.html"><span class="kw2066">std::<span class="me2">atomic</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">difference_type</span> arg,<br /></p>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<a href="cpp-atomic-memory_order.html"><span class="kw2088">std::<span class="me2">memory_order</span></span></a> order <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
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<p>&#36827;&#34892;&#21407;&#23376;&#20943;&#27861;&#12290;</p>
<p>&#21407;&#23376;&#22320;&#20174; <code>obj</code> &#25152;&#25351;&#21521;&#30340;&#20540;&#20943;&#21435; <code>arg</code> &#65292;&#24182;&#36820;&#22238; <code>obj</code> &#20808;&#21069;&#20445;&#26377;&#30340;&#20540;&#12290;&#22914;&#21516;&#25191;&#34892;&#19979;&#21015;&#20869;&#23481;&#19968;&#26679;&#36827;&#34892;&#36816;&#31639;&#65306;</p>
<div class="t-li2"><span class="t-li">1)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">obj<span class="sy2">-</span><span class="sy1">&gt;</span>fetch_sub<span class="br0">(</span>arg<span class="br0">)</span></span></span></div>
<div class="t-li2"><span class="t-li">2)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">obj<span class="sy2">-</span><span class="sy1">&gt;</span>fetch_sub<span class="br0">(</span>arg, order<span class="br0">)</span></span></span></div>
<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>obj</td>
<td>-</td>
<td>&#25351;&#21521;&#35201;&#20462;&#25913;&#30340;&#21407;&#23376;&#23545;&#35937;&#30340;&#25351;&#38024;</td>
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<tr class="t-par">
<td>arg</td>
<td>-</td>
<td>&#35201;&#20174;&#23384;&#20648;&#20110;&#21407;&#23376;&#23545;&#35937;&#30340;&#20540;&#20943;&#21435;&#30340;&#20540;</td>
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<td>order</td>
<td>-</td>
<td>&#27492;&#25805;&#20316;&#25152;&#29992;&#30340;&#20869;&#23384;&#21516;&#27493;&#39034;&#24207;&#65306;&#23481;&#35768;&#25152;&#26377;&#20540;&#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><code>*obj</code> &#30340;<a href="cpp-atomic-memory_order.html#.E4.BF.AE.E6.94.B9.E9.A1.BA.E5.BA.8F">&#20462;&#25913;&#39034;&#24207;</a>&#20013;&#31435;&#21363;&#21069;&#36235;&#27492;&#20989;&#25968;&#25928;&#26524;&#30340;&#20540;&#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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<div class="cpp source-cpp">
<pre class="de1"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> T <span class="sy1">&gt;</span>
T atomic_fetch_sub<span class="br0">(</span> <a href="cpp-atomic-atomic.html"><span class="kw2066">std::<span class="me2">atomic</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy2">*</span> obj,
<span class="kw1">typename</span> <a href="cpp-atomic-atomic.html"><span class="kw2066">std::<span class="me2">atomic</span></span></a><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">difference_type</span> arg <span class="br0">)</span> <span class="kw1">noexcept</span>
<span class="br0">{</span>
<span class="kw1">return</span> obj<span class="sy2">-</span><span class="sy1">&gt;</span>fetch_sub<span class="br0">(</span>arg<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
<div class="t-example">
<p>&#22810;&#20010;&#32447;&#31243;&#21487;&#29992; <code>fetch_sub</code> &#21516;&#26102;&#22788;&#29702;&#26377;&#19979;&#26631;&#30340;&#23481;&#22120;</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;string&gt;</span>
<span class="co2">#include &lt;thread&gt;</span>
<span class="co2">#include &lt;vector&gt;</span>
<span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;atomic&gt;</span>
<span class="co2">#include &lt;numeric&gt;</span>
<span class="kw4">const</span> <span class="kw4">int</span> N <span class="sy1">=</span> <span class="nu0">10000</span><span class="sy4">;</span>
<a href="cpp-atomic-atomic.html"><span class="kw2066">std::<span class="me2">atomic</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> cnt<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> data<span class="br0">(</span>N<span class="br0">)</span><span class="sy4">;</span>
<span class="kw4">void</span> reader<span class="br0">(</span><span class="kw4">int</span> id<span class="br0">)</span>
<span class="br0">{</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="sy4">;;</span><span class="br0">)</span> <span class="br0">{</span>
<span class="kw4">int</span> idx <span class="sy1">=</span> atomic_fetch_sub_explicit<span class="br0">(</span><span class="sy3">&amp;</span>cnt, <span class="nu0">1</span>, <a href="cpp-atomic-memory_order.html"><span class="kw2089">std::<span class="me2">memory_order_relaxed</span></span></a><span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">if</span> <span class="br0">(</span>idx <span class="sy1">&gt;=</span> <span class="nu0">0</span><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> <span class="st0">&quot;reader &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-string-basic_string-to_string.html"><span class="kw1265">std::<span class="me2">to_string</span></span></a><span class="br0">(</span>id<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot; processed item &quot;</span>
<span class="sy1">&lt;&lt;</span> <a href="cpp-string-basic_string-to_string.html"><span class="kw1265">std::<span class="me2">to_string</span></span></a><span class="br0">(</span>data<span class="br0">[</span>idx<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">else</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;reader &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-string-basic_string-to_string.html"><span class="kw1265">std::<span class="me2">to_string</span></span></a><span class="br0">(</span>id<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot; done<span class="es1">\n</span>&quot;</span><span class="sy4">;</span>
<span class="kw1">break</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span>
<span class="br0">}</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-algorithm-iota.html"><span class="kw1655">std::<span class="me2">iota</span></span></a><span class="br0">(</span>data.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, data.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
cnt <span class="sy1">=</span> data.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy2">-</span> <span class="nu0">1</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><a href="cpp-thread-thread.html"><span class="kw2142">std::<span class="me2">thread</span></span></a><span class="sy1">&gt;</span> v<span class="sy4">;</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> n <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> n <span class="sy1">&lt;</span> <span class="nu0">10</span><span class="sy4">;</span> <span class="sy2">++</span>n<span class="br0">)</span> <span class="br0">{</span>
v.<span class="me1">emplace_back</span><span class="br0">(</span>reader, n<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">auto</span><span class="sy3">&amp;</span> t <span class="sy4">:</span> v<span class="br0">)</span> <span class="br0">{</span>
t.<span class="me1">join</span><span class="br0">(</span><span class="br0">)</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">reader 2 processed item 10000
reader 6 processed item 9994
reader 4 processed item 9996
reader 6 processed item 9992
&lt;....&gt;
reader 0 done
reader 5 done
reader 3 done
reader 9 done</pre></div>
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<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">&#32570;&#38519;&#25253;&#21578;</span></h3>
<p>&#19979;&#21015;&#26356;&#25913;&#34892;&#20026;&#30340;&#32570;&#38519;&#25253;&#21578;&#36861;&#28335;&#22320;&#24212;&#29992;&#20110;&#20197;&#21069;&#20986;&#29256;&#30340; C++ &#26631;&#20934;&#12290;</p>
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<th>DR</th>
<th>&#24212;&#29992;&#20110;</th>
<th>&#20986;&#29256;&#26102;&#30340;&#34892;&#20026;</th>
<th>&#27491;&#30830;&#34892;&#20026;</th>
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<tr>
<td><a rel="nofollow" class="external text" href="https://wg21.link/P0558R1">P0558R1</a></td>
<td>C++11</td>
<td>&#26366;&#35201;&#27714;&#20934;&#30830;&#31867;&#22411;&#21305;&#37197;&#65292;&#22240;&#20026;&#20174;&#22810;&#20010;&#21442;&#25968;&#25512;&#23548; <code>T</code></td>
<td>&#20165;&#20174; <code>atomic</code> &#21442;&#25968;&#25512;&#23548; <code>T</code></td>
</tr>
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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 class="t-dsc-member-div">
<div><a href="cpp-atomic-atomic-fetch_sub.html"><span class="t-lines"><span>fetch_sub</span></span></a></div>
</div>
</td>
<td>&#21407;&#23376;&#22320;&#20174;&#23384;&#20648;&#20110;&#21407;&#23376;&#23545;&#35937;&#30340;&#20540;&#20943;&#21435;&#21442;&#25968;&#65292;&#24182;&#33719;&#24471;&#20808;&#21069;&#20445;&#26377;&#30340;&#20540;<br />
<span class="t-mark">(<code>std::atomic&lt;T&gt;</code> &#30340;&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-atomic-atomic_fetch_add.html"><span class="t-lines"><span>atomic_fetch_add</span><span>atomic_fetch_add_explicit</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-cxx11">(C++11)</span></span></span></div>
</div>
</td>
<td>&#23558;&#38750;&#21407;&#23376;&#20540;&#21152;&#21040;&#21407;&#23376;&#23545;&#35937;&#65292;&#24182;&#33719;&#24471;&#21407;&#23376;&#23545;&#35937;&#30340;&#20808;&#21069;&#20540;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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