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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::atomic&lt;T&gt;::</span>fetch_add</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>&lrm; | <a href="cpp-atomic-atomic.html">atomic</a></span></div>
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<div>&#20165;&#20026; <code>atomic&lt;<i>Integral</i>&gt;</code><span class="t-mark-rev t-since-cxx11">(C++11)</span> &#19982; <code>atomic&lt;<i>Floating</i>&gt;</code><span class="t-mark-rev t-since-cxx20">(C++20)</span> &#27169;&#26495;&#29305;&#21270;&#30340;&#25104;&#21592;</div>
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<td rowspan="142">(1)</td>
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<div><span class="mw-geshi cpp source-cpp">T fetch_add<span class="br0">(</span> T arg,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<a href="cpp-atomic-memory_order.html"><span class="kw2092">std::<span class="me2">memory_order</span></span></a> order <span class="sy1">=</span> <a href="cpp-atomic-memory_order.html"><span class="kw2098">std::<span class="me2">memory_order_seq_cst</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<div><span class="mw-geshi cpp source-cpp">T fetch_add<span class="br0">(</span> T arg,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<a href="cpp-atomic-memory_order.html"><span class="kw2092">std::<span class="me2">memory_order</span></span></a> order <span class="sy1">=</span> <a href="cpp-atomic-memory_order.html"><span class="kw2098">std::<span class="me2">memory_order_seq_cst</span></span></a> <span class="br0">)</span> <span class="kw4">volatile</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<div>&#20165;&#20026; <code>atomic&lt;T*&gt;</code> &#27169;&#26495;&#29305;&#21270;&#30340;&#25104;&#21592;</div>
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<td rowspan="142">(2)</td>
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<div><span class="mw-geshi cpp source-cpp">T<span class="sy2">*</span> fetch_add<span class="br0">(</span> <a href="cpp-types-ptrdiff_t.html"><span class="kw101">std::<span class="me2">ptrdiff_t</span></span></a> arg,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <a href="cpp-atomic-memory_order.html"><span class="kw2092">std::<span class="me2">memory_order</span></span></a> order <span class="sy1">=</span> <a href="cpp-atomic-memory_order.html"><span class="kw2098">std::<span class="me2">memory_order_seq_cst</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<div><span class="mw-geshi cpp source-cpp">T<span class="sy2">*</span> fetch_add<span class="br0">(</span> <a href="cpp-types-ptrdiff_t.html"><span class="kw101">std::<span class="me2">ptrdiff_t</span></span></a> arg,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <a href="cpp-atomic-memory_order.html"><span class="kw2092">std::<span class="me2">memory_order</span></span></a> order <span class="sy1">=</span> <a href="cpp-atomic-memory_order.html"><span class="kw2098">std::<span class="me2">memory_order_seq_cst</span></span></a> <span class="br0">)</span> <span class="kw4">volatile</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<p>&#21407;&#23376;&#22320;&#20197;&#20540;&#21644; <code>arg</code> &#30340;&#31639;&#26415;&#21152;&#27861;&#32467;&#26524;&#26367;&#25442;&#24403;&#21069;&#20540;&#12290;&#36816;&#31639;&#26159;&#35835;&#20462;&#25913;&#20889;&#25805;&#20316;&#12290;&#25353;&#29031; <code>order</code> &#30340;&#20540;&#24433;&#21709;&#20869;&#23384;&#12290;</p>
<p>&#23545;&#20110;&#26377;&#31526;&#21495; <code>Integral</code> &#31867;&#22411;&#65292;&#23450;&#20041;&#31639;&#26415;&#20026;&#20351;&#29992;&#34917;&#30721;&#12290;&#26080;&#26410;&#23450;&#20041;&#32467;&#26524;&#12290;</p>
<p>&#23545;&#20110; <code>T*</code> &#31867;&#22411;&#65292;&#32467;&#26524;&#21487;&#33021;&#20026;&#26410;&#23450;&#20041;&#30340;&#22320;&#22336;&#65292;&#20294;&#27492;&#22806;&#36816;&#31639;&#26080;&#26410;&#23450;&#20041;&#34892;&#20026;&#12290;</p>
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<p>&#23545;&#20110;&#28014;&#28857;&#31867;&#22411;&#65292;&#26377;&#24433;&#21709;&#30340;<a href="cpp-numeric-fenv.html">&#28014;&#28857;&#29615;&#22659;</a>&#21487;&#33021;&#24322;&#20110;&#35843;&#29992;&#26041;&#32447;&#31243;&#30340;&#28014;&#28857;&#29615;&#22659;&#12290;&#25805;&#20316;&#19981;&#24517;&#36981;&#24490;&#23545;&#24212;&#30340; <span class="t-lc"><a href="cpp-types-numeric_limits.html">std::numeric_limits</a></span> &#29305;&#24615;&#65292;&#20294;&#40723;&#21169;&#36825;&#20040;&#20570;&#12290;&#33509;&#32467;&#26524;&#19981;&#26159;&#20854;&#31867;&#22411;&#25152;&#33021;&#34920;&#31034;&#30340;&#20540;&#65292;&#21017;&#32467;&#26524;&#26410;&#25351;&#23450;&#65292;&#20294;&#27492;&#22806;&#25805;&#20316;&#26080;&#26410;&#23450;&#20041;&#34892;&#20026;&#12290;</p>
<p>&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><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">is_always_lock_free</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#21017; volatile &#38480;&#23450;&#29256;&#26412;&#34987;&#24323;&#29992;&#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>arg</td>
<td>-</td>
<td>&#31639;&#26415;&#21152;&#27861;&#30340;&#21478;&#19968;&#21442;&#25968;</td>
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<td>order</td>
<td>-</td>
<td>&#24378;&#21046;&#30340;&#20869;&#23384;&#39034;&#24207;&#21046;&#32422;</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>*this</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;&#65292;&#31435;&#21363;&#21069;&#36235;&#27492;&#20989;&#25968;&#25928;&#24212;&#30340;&#20540;&#12290;</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;iostream&gt;</span>
<span class="co2">#include &lt;thread&gt;</span>
<span class="co2">#include &lt;atomic&gt;</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">long</span> <span class="kw4">long</span><span class="sy1">&gt;</span> data<span class="sy4">;</span>
<span class="kw4">void</span> do_work<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
data.<span class="me1">fetch_add</span><span class="br0">(</span><span class="nu0">1</span>, <a href="cpp-atomic-memory_order.html"><span class="kw2093">std::<span class="me2">memory_order_relaxed</span></span></a><span class="br0">)</span><span class="sy4">;</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-thread-thread.html"><span class="kw2146">std::<span class="me2">thread</span></span></a> th1<span class="br0">(</span>do_work<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-thread-thread.html"><span class="kw2146">std::<span class="me2">thread</span></span></a> th2<span class="br0">(</span>do_work<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-thread-thread.html"><span class="kw2146">std::<span class="me2">thread</span></span></a> th3<span class="br0">(</span>do_work<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-thread-thread.html"><span class="kw2146">std::<span class="me2">thread</span></span></a> th4<span class="br0">(</span>do_work<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-thread-thread.html"><span class="kw2146">std::<span class="me2">thread</span></span></a> th5<span class="br0">(</span>do_work<span class="br0">)</span><span class="sy4">;</span>
th1.<span class="me1">join</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
th2.<span class="me1">join</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
th3.<span class="me1">join</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
th4.<span class="me1">join</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
th5.<span class="me1">join</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;Result:&quot;</span> <span class="sy1">&lt;&lt;</span> data <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>
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<pre class="de1">Result:5</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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<td><a rel="nofollow" class="external text" href="https://wg21.link/P0558R1">P0558R1</a></td>
<td>C++11</td>
<td>&#26366;&#23481;&#35768;&#25351;&#21521; <i>cv</i> void &#25110;&#20989;&#25968;&#30340;&#25351;&#38024;</td>
<td>&#20351;&#20043;&#20026;&#35884;&#26500;</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-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>
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<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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