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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>memcpy</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-byte.html">byte</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-cstring.html">&lt;cstring&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span><span class="sy2">*</span> memcpy<span class="br0">(</span> <span class="kw4">void</span><span class="sy2">*</span> dest, <span class="kw4">const</span> <span class="kw4">void</span><span class="sy2">*</span> src, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> count <span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>&#20174; <code>src</code> &#25152;&#25351;&#21521;&#30340;&#23545;&#35937;&#22797;&#21046; <code>count</code> &#20010;&#23383;&#31526;&#21040; <code>dest</code> &#25152;&#25351;&#21521;&#30340;&#23545;&#35937;&#12290;&#20004;&#20010;&#23545;&#35937;&#37117;&#34987;&#36716;&#35793;&#25104; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">char</span></span></span> &#30340;&#25968;&#32452;&#12290;</p>
<p>&#33509;&#23545;&#35937;&#37325;&#21472;&#65292;&#21017;&#34892;&#20026;&#26410;&#23450;&#20041;&#12290;</p>
<p>&#33509; <code>dest</code> &#25110; <code>src</code> &#20026;<a href="cpp-language-pointer.html#.E6.8C.87.E9.92.88">&#38750;&#27861;&#25110;&#31354;&#25351;&#38024;</a>&#21017;&#34892;&#20026;&#26410;&#23450;&#20041;&#65292;&#32437;&#20351; <code>count</code> &#20026;&#38646;&#12290;</p>
<p>&#33509;&#23545;&#35937;<a href="cpp-language-object.html#.E5.AD.90.E5.AF.B9.E8.B1.A1">&#28508;&#22312;&#37325;&#21472;</a>&#25110;&#19981;<a href="cpp-named_req-TriviallyCopyable.html"><span style="font-style:italic">&#21487;&#24179;&#20961;&#22797;&#21046;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(TriviallyCopyable)</span></a> &#65292;&#21017; <code>memcpy</code> &#30340;&#34892;&#20026;&#26410;&#25351;&#23450;&#32780;&#19988;<a rel="nofollow" class="external text" href="http://stackoverflow.com/questions/29777492">&#21487;&#33021;&#26410;&#23450;&#20041;</a>&#12290;</p>
<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>dest</td>
<td>-</td>
<td>&#25351;&#21521;&#35201;&#22797;&#21046;&#30340;&#23545;&#35937;&#30340;&#25351;&#38024;</td>
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<tr class="t-par">
<td>src</td>
<td>-</td>
<td>&#25351;&#21521;&#22797;&#21046;&#26469;&#28304;&#23545;&#35937;&#30340;&#25351;&#38024;</td>
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<tr class="t-par">
<td>count</td>
<td>-</td>
<td>&#22797;&#21046;&#30340;&#23383;&#33410;&#25968;</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>dest</code></p>
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<p><code>std::memcpy</code> &#21487;&#29992;&#20110;&#22312;&#30446;&#26631;&#32531;&#20914;&#21306;&#20013;<a href="cpp-language-object.html#.E5.AF.B9.E8.B1.A1.E5.88.9B.E5.BB.BA">&#38544;&#24335;&#21019;&#24314;</a>&#23545;&#35937;&#12290;</p>
<p><code>std::memcpy</code> &#29702;&#24212;&#26159;&#26368;&#24555;&#30340;&#20869;&#23384;&#21040;&#20869;&#23384;&#22797;&#21046;&#23376;&#31243;&#24207;&#12290;&#23427;&#36890;&#24120;&#27604;&#24517;&#39035;&#25195;&#25551;&#20854;&#25152;&#22797;&#21046;&#25968;&#25454;&#30340; <span class="t-lc"><a href="cpp-string-byte-strcpy.html">std::strcpy</a></span> &#65292;&#25110;&#24517;&#39035;&#39044;&#38450;&#20197;&#22788;&#29702;&#37325;&#21472;&#36755;&#20837;&#30340; <span class="t-lc"><a href="cpp-string-byte-memmove.html">std::memmove</a></span> &#26356;&#39640;&#25928;&#12290;</p>
<p>&#35768;&#22810; C++ &#32534;&#35793;&#22120;&#23558;&#36866;&#21512;&#30340;&#20869;&#23384;&#22797;&#21046;&#24490;&#29615;&#21464;&#25442;&#20026; <code>std::memcpy</code> &#35843;&#29992;&#12290;</p>
<p>&#22312;<a href="cpp-language-object.html#.E4.B8.A5.E6.A0.BC.E7.9A.84.E5.88.AB.E5.90.8D.E4.BD.BF.E7.94.A8">&#20005;&#26684;&#21035;&#21517;&#20351;&#29992;</a>&#31105;&#27490;&#26816;&#39564;&#21516;&#19968;&#20869;&#23384;&#20026;&#20108;&#20010;&#19981;&#21516;&#31867;&#22411;&#30340;&#20540;&#22788;&#65292;&#21487;&#29992; <code>std::memcpy</code> &#36716;&#25442;&#20540;&#12290;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
<div class="t-example">
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<div class="cpp source-cpp">
<pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;cstdint&gt;</span>
<span class="co2">#include &lt;cstring&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="co1">// &#31616;&#21333;&#29992;&#27861;</span>
<span class="kw4">char</span> source<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <span class="st0">&quot;once upon a midnight dreary...&quot;</span>, dest<span class="br0">[</span><span class="nu0">4</span><span class="br0">]</span><span class="sy4">;</span>
std<span class="sy4">::</span><span class="me2">memcpy</span><span class="br0">(</span>dest, source, sizeof dest<span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">char</span> c <span class="sy4">:</span> dest<span class="br0">)</span>
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> c <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="co1">// &#36716;&#35793;</span>
<span class="kw4">double</span> d <span class="sy1">=</span> <span class="nu16">0.1</span><span class="sy4">;</span>
<span class="co1">// std::int64_t n = *reinterpret_cast&lt;std::int64_t*&gt;(&amp;d); // &#21035;&#21517;&#36829;&#35268;</span>
<a href="cpp-types-integer.html"><span class="kw109">std::<span class="me2">int64_t</span></span></a> n<span class="sy4">;</span>
std<span class="sy4">::</span><span class="me2">memcpy</span><span class="br0">(</span><span class="sy3">&amp;</span>n, <span class="sy3">&amp;</span>d, sizeof d<span class="br0">)</span><span class="sy4">;</span> <span class="co1">// OK</span>
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <a href="cpp-io-manip-fixed.html"><span class="kw1785">std::<span class="me2">hexfloat</span></span></a> <span class="sy1">&lt;&lt;</span> d <span class="sy1">&lt;&lt;</span> <span class="st0">&quot; is &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-io-manip-hex.html"><span class="kw1781">std::<span class="me2">hex</span></span></a> <span class="sy1">&lt;&lt;</span> n
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; as an std::int64_t<span class="es1">\n</span>&quot;</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">o
n
c
e
0x1.999999999999ap-4 is 3fb999999999999a as an std::int64_t</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-byte-memmove.html"><span class="t-lines"><span>memmove</span></span></a></div>
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<td>&#31227;&#21160;&#19968;&#20010;&#32531;&#20914;&#21306;&#21040;&#21478;&#19968;&#20010;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<div class="t-dsc-member-div">
<div><a href="cpp-string-byte-memset.html"><span class="t-lines"><span>memset</span></span></a></div>
</div>
</td>
<td>&#20197;&#19968;&#20010;&#23383;&#31526;&#22635;&#20805;&#32531;&#20914;&#21306;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<div class="t-dsc-member-div">
<div><a href="cpp-string-wide-wmemcpy.html"><span class="t-lines"><span>wmemcpy</span></span></a></div>
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<td>&#22312;&#20004;&#20010;&#19981;&#37325;&#21472;&#25968;&#32452;&#38388;&#22797;&#21046;&#19968;&#23450;&#37327;&#23485;&#23383;&#31526;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-copy.html"><span class="t-lines"><span>copy</span><span>copy_if</span></span></a></div>
<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>&#23558;&#26576;&#19968;&#33539;&#22260;&#30340;&#20803;&#32032;&#22797;&#21046;&#21040;&#19968;&#20010;&#26032;&#30340;&#20301;&#32622;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-copy_backward.html"><span class="t-lines"><span>copy_backward</span></span></a></div>
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<td>&#25353;&#20174;&#21518;&#24448;&#21069;&#30340;&#39034;&#24207;&#22797;&#21046;&#19968;&#20010;&#33539;&#22260;&#20869;&#30340;&#20803;&#32032;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-types-is_trivially_copyable.html"><span class="t-lines"><span>is_trivially_copyable</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
</div>
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<td>&#26816;&#26597;&#31867;&#22411;&#26159;&#21542;&#21487;&#24179;&#20961;&#22797;&#21046;<br />
<span class="t-mark">(&#31867;&#27169;&#26495;)</span></td>
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