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<!DOCTYPE html>
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>memccpy</title>
<link rel="stylesheet" href="ext.css" />
<link rel="stylesheet" href="site_modules.css" />
</head>
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_string_byte_memccpy skin-cppreference2 action-view cpp-navbar">
<div id="cpp-content-base">
<div id="content"><a id="top"></a>
<h1 id="firstHeading" class="firstHeading">memccpy</h1>
<div id="bodyContent">
<div id="contentSub"><span class="subpages">&lt; <a href="c.html">c</a>&lrm; | <a href="c-string.html">string</a>&lrm; | <a href="c-string-byte.html">byte</a></span></div>
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
<table class="t-dcl-begin">
<tbody>
<tr class="t-dsc-header">
<td>
<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code>&lt;string.h&gt;</code></div>
</td>
<td></td>
<td></td>
</tr>
<tr class="t-dcl t-since-c23">
<td>
<div><span class="mw-geshi c source-c"><span class="kw4">void</span> <span class="sy2">*</span>memccpy<span class="br0">(</span><span class="kw4">void</span> <span class="sy2">*</span> <span class="kw4">restrict</span> dest, <span class="kw4">const</span> <span class="kw4">void</span> <span class="sy2">*</span> <span class="kw4">restrict</span> src, <span class="kw4">int</span> c, <a href="c-types-size_t.html"><span class="kw100">size_t</span></a> count<span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-c23">(C23 &#36215;)</span></td>
</tr>
<tr class="t-dcl-sep">
<td></td>
<td></td>
<td></td>
</tr>
</tbody>
</table>
<p>&#20174; <code>src</code> &#25152;&#25351;&#21521;&#30340;&#23545;&#35937;&#22797;&#21046;&#23383;&#31526;&#21040; <code>dest</code> &#25152;&#25351;&#21521;&#30340;&#23545;&#35937;&#65292;&#22312;&#28385;&#36275;&#25509;&#19979;&#26469;&#30340;<i>&#20219;&#20309;</i>&#20004;&#20010;&#26465;&#20214;&#20043;&#19968;&#21518;&#20572;&#27490;&#65306;</p>
<dl>
<dd>
<ul>
<li>&#22797;&#21046;&#20102; <code>count</code> &#20010;&#23383;&#31526;</li>
<li>&#25214;&#21040;&#65288;&#24182;&#22797;&#21046;&#65289;&#20102;&#23383;&#31526; <span class="t-c"><span class="mw-geshi c source-c"><span class="br0">(</span><span class="kw4">unsigned</span> <span class="kw4">char</span><span class="br0">)</span>c</span></span> &#12290;</li>
</ul>
</dd>
</dl>
<p>&#36716;&#35793; <code>src</code> &#19982; <code>dest</code> &#23545;&#35937;&#20026; <span class="t-c"><span class="mw-geshi c source-c"><span class="kw4">unsigned</span> <span class="kw4">char</span></span></span> &#30340;&#25968;&#32452;&#12290;</p>
<p>&#33509;&#31526;&#21512;<i>&#20219;&#20309;</i>&#20197;&#19979;&#26465;&#20214;&#21017;&#34892;&#20026;&#26410;&#23450;&#20041;&#65306;</p>
<dl>
<dd>
<ul>
<li>&#20986;&#29616;&#36234;&#36807; <code>dest</code> &#25968;&#32452;&#32467;&#23614;&#30340;&#35775;&#38382;</li>
<li>&#23545;&#35937;&#37325;&#21472;&#65288;&#36825;&#36829;&#21453; <a href="c-language-restrict.html"><tt>restrict</tt></a> &#22865;&#32422;&#65289;</li>
<li><code>dest</code> &#25110; <code>src</code> &#20026;&#38750;&#27861;&#25110;&#31354;&#25351;&#38024;&#20540;</li>
</ul>
</dd>
</dl>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
<table class="t-par-begin">
<tr class="t-par">
<td>dest</td>
<td>-</td>
<td>&#25351;&#21521;&#35201;&#22797;&#21046;&#30340;&#23545;&#35937;&#30340;&#25351;&#38024;</td>
</tr>
<tr class="t-par">
<td>src</td>
<td>-</td>
<td>&#25351;&#21521;&#22797;&#21046;&#26469;&#28304;&#23545;&#35937;&#30340;&#25351;&#38024;</td>
</tr>
<tr class="t-par">
<td>c</td>
<td>-</td>
<td>&#32456;&#27490;&#23383;&#31526;&#65292;&#39318;&#20808;&#36716;&#25442;&#25104; <span class="t-c"><span class="mw-geshi c source-c"><span class="kw4">unsigned</span> <span class="kw4">char</span></span></span></td>
</tr>
<tr class="t-par">
<td>count</td>
<td>-</td>
<td>&#35201;&#22797;&#21046;&#30340;&#23383;&#31526;&#25968;</td>
</tr>
</table>
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#33509;&#25214;&#21040;&#23383;&#31526; <span class="t-c"><span class="mw-geshi c source-c"><span class="br0">(</span><span class="kw4">unsigned</span> <span class="kw4">char</span><span class="br0">)</span>c</span></span> &#21017; <code>memccpy</code> &#36820;&#22238; <code>dest</code> &#20013; <span class="t-c"><span class="mw-geshi c source-c"><span class="br0">(</span><span class="kw4">unsigned</span> <span class="kw4">char</span><span class="br0">)</span>c</span></span> &#21518;&#19968;&#23383;&#31526;&#30340;&#25351;&#38024;&#65292;&#21542;&#21017;&#36820;&#22238;&#31354;&#25351;&#38024;&#12290;</p>
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<p>&#20989;&#25968;&#31561;&#21516;&#20110; <a rel="nofollow" class="external text" href="https://pubs.opengroup.org/onlinepubs/9699919799/functions/memccpy.html">POSIX memccpy</a> &#12290;</p>
<p><span class="t-c"><span class="mw-geshi c source-c">memccpy<span class="br0">(</span>dest, src, <span class="nu0">0</span>, count<span class="br0">)</span></span></span> &#34920;&#29616;&#31867;&#20284; <span class="t-c"><span class="mw-geshi c source-c"><a href="c-string-byte-strncpy.html"><span class="kw554">strncpy</span></a><span class="br0">(</span>dest, src, count<span class="br0">)</span></span></span> &#65292;&#38500;&#20102;&#21069;&#32773;&#36820;&#22238;&#25351;&#21521;&#34987;&#20889;&#20837;&#32531;&#20914;&#21306;&#30340;<i>&#26411;&#23614;</i>&#30340;&#25351;&#38024;&#65292;&#24182;&#19988;&#19981;&#20250;&#20197;&#38646;&#22635;&#20805;&#30446;&#26631;&#25968;&#32452;&#12290;&#20174;&#32780; <code>memccpy</code> &#23545;&#39640;&#25928;&#36830;&#25509;&#22810;&#20010;&#23383;&#31526;&#20018;&#26377;&#29992;&#12290;</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="c source-c">
<pre class="de1"><span class="kw4">char</span> bigString<span class="br0">[</span><span class="nu0">1000</span><span class="br0">]</span><span class="sy4">;</span>
<span class="kw4">char</span><span class="sy2">*</span> end <span class="sy1">=</span> bigString <span class="sy2">+</span> <span class="kw4">sizeof</span> bigString<span class="sy4">;</span>
<span class="kw4">char</span><span class="sy2">*</span> p <span class="sy1">=</span> memccpy<span class="br0">(</span>bigString, <span class="st0">&quot;John, &quot;</span>, <span class="nu0">0</span>, <span class="kw4">sizeof</span> bigString<span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">if</span> <span class="br0">(</span>p<span class="br0">)</span> p <span class="sy1">=</span> memccpy<span class="br0">(</span>p <span class="sy2">-</span> <span class="nu0">1</span>, <span class="st0">&quot;Paul, &quot;</span>, <span class="nu0">0</span>, end <span class="sy2">-</span> p<span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">if</span> <span class="br0">(</span>p<span class="br0">)</span> p <span class="sy1">=</span> memccpy<span class="br0">(</span>p <span class="sy2">-</span> <span class="nu0">1</span>, <span class="st0">&quot;George, &quot;</span>, <span class="nu0">0</span>, end <span class="sy2">-</span> p<span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">if</span> <span class="br0">(</span>p<span class="br0">)</span> p <span class="sy1">=</span> memccpy<span class="br0">(</span>p <span class="sy2">-</span> <span class="nu0">1</span>, <span class="st0">&quot;Joel &quot;</span>, <span class="nu0">0</span>, end <span class="sy2">-</span> p<span class="br0">)</span><span class="sy4">;</span>
<a href="c-io-puts.html"><span class="kw836">puts</span></a><span class="br0">(</span>bigString<span class="br0">)</span><span class="sy4">;</span> <span class="co1">// John, Paul, George, Joel</span></pre></div>
</div>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
<div class="t-example">
<div class="t-example-live-link"></div>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="c source-c">
<pre class="de1"><span class="co2">#include &lt;ctype.h&gt;</span>
<span class="co2">#include &lt;stdio.h&gt;</span>
<span class="co2">#include &lt;string.h&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw4">const</span> <span class="kw4">char</span> src<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <span class="st0">&quot;Stars: Altair, Sun, Vega.&quot;</span><span class="sy4">;</span>
<span class="kw4">const</span> <span class="kw4">char</span> terminal<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <span class="br0">{</span><span class="st0">&#39;:&#39;</span>, <span class="st0">&#39; &#39;</span>, <span class="st0">&#39;,&#39;</span>, <span class="st0">&#39;.&#39;</span>, <span class="st0">&#39;!&#39;</span><span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">char</span> dest<span class="br0">[</span><span class="kw4">sizeof</span> src<span class="br0">]</span><span class="sy4">;</span>
<span class="kw4">const</span> <span class="kw4">char</span> alt <span class="sy1">=</span> <span class="st0">&#39;@&#39;</span><span class="sy4">;</span>
<span class="kw1">for</span> <span class="br0">(</span><a href="c-types-size_t.html"><span class="kw100">size_t</span></a> i <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> i <span class="sy3">!</span><span class="sy1">=</span> <span class="kw4">sizeof</span> terminal<span class="sy4">;</span> <span class="sy2">++</span>i<span class="br0">)</span> <span class="br0">{</span>
<span class="kw4">void</span> <span class="sy2">*</span>to <span class="sy1">=</span> memccpy<span class="br0">(</span>dest, src, terminal<span class="br0">[</span>i<span class="br0">]</span>, <span class="kw4">sizeof</span> dest<span class="br0">)</span><span class="sy4">;</span>
<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">&quot;Terminal &#39;%c&#39; (%s):<span class="es1">\t</span><span class="es1">\&quot;</span>&quot;</span>, terminal<span class="br0">[</span>i<span class="br0">]</span>, to <span class="sy4">?</span> <span class="st0">&quot;found&quot;</span> <span class="sy4">:</span> <span class="st0">&quot;absent&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<span class="co1">// &#33509;&#25214;&#19981;&#21040; `terminal` &#23383;&#31526; - &#25171;&#21360;&#25972;&#20010; `dest`</span>
to <span class="sy1">=</span> to <span class="sy4">?</span> to <span class="sy4">:</span> dest <span class="sy2">+</span> <span class="kw4">sizeof</span> dest<span class="sy4">;</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">char</span> <span class="sy2">*</span>from <span class="sy1">=</span> dest<span class="sy4">;</span> from <span class="sy3">!</span><span class="sy1">=</span> to<span class="sy4">;</span> <span class="sy2">++</span>from<span class="br0">)</span>
<a href="c-io-putchar.html"><span class="kw835">putchar</span></a><span class="br0">(</span><a href="c-string-byte-isprint.html"><span class="kw536">isprint</span></a><span class="br0">(</span><span class="sy2">*</span>from<span class="br0">)</span> <span class="sy4">?</span> <span class="sy2">*</span>from <span class="sy4">:</span> alt<span class="br0">)</span><span class="sy4">;</span>
<a href="c-io-puts.html"><span class="kw836">puts</span></a><span class="br0">(</span><span class="st0">&quot;<span class="es1">\&quot;</span>&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<a href="c-io-puts.html"><span class="kw836">puts</span></a><span class="br0">(</span><span class="st0">&quot;<span class="es1">\n</span>&quot;</span> <span class="st0">&quot;Separate star names from distances (ly):&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>star_distance<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <span class="br0">{</span>
<span class="st0">&quot;Arcturus : 37&quot;</span>, <span class="st0">&quot;Vega : 25&quot;</span>, <span class="st0">&quot;Capella : 43&quot;</span>, <span class="st0">&quot;Rigel : 860&quot;</span>, <span class="st0">&quot;Procyon : 11&quot;</span>
<span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">char</span> names_only<span class="br0">[</span><span class="nu0">64</span><span class="br0">]</span><span class="sy4">;</span>
<span class="kw4">char</span> <span class="sy2">*</span>first <span class="sy1">=</span> names_only<span class="sy4">;</span>
<span class="kw4">char</span> <span class="sy2">*</span>last <span class="sy1">=</span> names_only <span class="sy2">+</span> <span class="kw4">sizeof</span> names_only<span class="sy4">;</span>
<span class="kw1">for</span> <span class="br0">(</span><a href="c-types-size_t.html"><span class="kw100">size_t</span></a> t <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> t <span class="sy3">!</span><span class="sy1">=</span> <span class="br0">(</span><span class="kw4">sizeof</span> star_distance<span class="br0">)</span><span class="sy2">/</span><span class="br0">(</span><span class="kw4">sizeof</span> star_distance<span class="br0">[</span><span class="nu0">0</span><span class="br0">]</span><span class="br0">)</span><span class="sy4">;</span> <span class="sy2">++</span>t<span class="br0">)</span> <span class="br0">{</span>
<span class="kw1">if</span> <span class="br0">(</span>first<span class="br0">)</span> <span class="br0">{</span>
first <span class="sy1">=</span> memccpy<span class="br0">(</span>first, star_distance<span class="br0">[</span>t<span class="br0">]</span>, <span class="st0">&#39; &#39;</span>, last <span class="sy2">-</span> first<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span> <span class="kw1">else</span> <span class="kw1">break</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">if</span> <span class="br0">(</span>first<span class="br0">)</span> <span class="br0">{</span>
<span class="sy2">*</span>first <span class="sy1">=</span> <span class="st0">&#39;<span class="es5">\0</span>&#39;</span><span class="sy4">;</span>
<a href="c-io-puts.html"><span class="kw836">puts</span></a><span class="br0">(</span>names_only<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span> <span class="kw1">else</span> <span class="br0">{</span>
<a href="c-io-puts.html"><span class="kw836">puts</span></a><span class="br0">(</span><span class="st0">&quot;Buffer is too small.&quot;</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">Terminal &#39;:&#39; (found): &quot;Stars:&quot;
Terminal &#39; &#39; (found): &quot;Stars: &quot;
Terminal &#39;,&#39; (found): &quot;Stars: Altair,&quot;
Terminal &#39;.&#39; (found): &quot;Stars: Altair, Sun, Vega.&quot;
Terminal &#39;!&#39; (absent): &quot;Stars: Altair, Sun, Vega.@&quot;
Separate star names from distances (ly):
Arcturus Vega Capella Rigel Procyon</pre></div>
</div>
</div>
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
<table class="t-dsc-begin">
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="c-string-byte-memcpy.html"><span class="t-lines"><span>memcpy</span><span>memcpy_s</span></span></a></div>
<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div>
</div>
</td>
<td>&#23558;&#19968;&#20010;&#32531;&#20914;&#21306;&#22797;&#21046;&#21040;&#21478;&#19968;&#20010;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="c-string-wide-wmemcpy.html"><span class="t-lines"><span>wmemcpy</span><span>wmemcpy_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div>
</div>
</td>
<td>&#22312;&#20004;&#20010;&#19981;&#37325;&#21472;&#30340;&#25968;&#32452;&#38388;&#22797;&#21046;&#19968;&#23450;&#25968;&#37327;&#30340;&#23485;&#23383;&#31526;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="c-string-byte-memmove.html"><span class="t-lines"><span>memmove</span><span>memmove_s</span></span></a></div>
<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div>
</div>
</td>
<td>&#23558;&#19968;&#20010;&#32531;&#20914;&#21306;&#31227;&#21160;&#21040;&#21478;&#19968;&#20010;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="c-string-byte-strcpy.html"><span class="t-lines"><span>strcpy</span><span>strcpy_s</span></span></a></div>
<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div>
</div>
</td>
<td>&#22797;&#21046;&#19968;&#20010;&#23383;&#31526;&#20018;&#32473;&#21478;&#19968;&#20010;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="c-string-byte-strcat.html"><span class="t-lines"><span>strcat</span><span>strcat_s</span></span></a></div>
<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div>
</div>
</td>
<td>&#36830;&#25509;&#20004;&#20010;&#23383;&#31526;&#20018;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
</table>
</div>
<div class="visualClear"></div>
</div>
</div>
</div>
</body>
</html>
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