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hustoj/web/cppreference-zh/chmhelp/c-string-byte-strndup.html
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<h1 id="firstHeading" class="firstHeading">strndup</h1>
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<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>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code>&lt;string.h&gt;</code></div>
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<div><span class="mw-geshi c source-c"><span class="kw4">char</span> <span class="sy2">*</span>strndup<span class="br0">(</span> <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>src, <a href="c-types-size_t.html"><span class="kw100">size_t</span></a> size <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-c23">(C23 &#36215;)</span></td>
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<p>&#36820;&#22238;&#25351;&#21521;&#21547;&#26377;&#26469;&#33258; <code>src</code> &#25152;&#25351;&#21521;&#30340;&#23383;&#31526;&#20018;&#30340;&#33267;&#22810; <code>size</code> &#20010;&#23383;&#33410;&#30340;&#21103;&#26412;&#30340;&#31354;&#32456;&#27490;&#23383;&#33410;&#23383;&#31526;&#20018;&#30340;&#25351;&#38024;&#12290;&#22914;&#21516;&#36890;&#36807;&#35843;&#29992; <span class="t-lc"><a href="c-memory-malloc.html">malloc</a></span> &#33719;&#24471;&#26032;&#23383;&#31526;&#20018;&#30340;&#31354;&#38388;&#12290;&#33509;&#22312;&#39318; <code>size</code> &#20010;&#23383;&#33410;&#20013;&#26410;&#36935;&#21040;&#31354;&#32456;&#27490;&#31526;&#65292;&#21017;&#23558;&#23427;&#21518;&#38468;&#21040;&#22797;&#21046;&#30340;&#23383;&#31526;&#20018;&#12290;</p>
<p>&#24517;&#39035;&#23558;&#36820;&#22238;&#30340;&#25351;&#38024;&#20256;&#36882;&#32473; <span class="t-lc"><a href="c-memory-free.html">free</a></span> &#20197;&#36991;&#20813;&#20869;&#23384;&#27844;&#28431;&#12290;</p>
<p>&#33509;&#20986;&#29616;&#38169;&#35823;&#65292;&#21017;&#36820;&#22238;&#31354;&#25351;&#38024;&#20540;&#24182;&#21487;&#33021;&#35774;&#32622; <span class="t-lc"><a href="c-error-errno.html">errno</a></span> &#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>src</td>
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<td>&#25351;&#21521;&#35201;&#22797;&#21046;&#30340;&#31354;&#32456;&#27490;&#23383;&#33410;&#23383;&#31526;&#20018;&#30340;&#25351;&#38024;</td>
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<td>size</td>
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<td>&#35201;&#20174; <code>src</code> &#22797;&#21046;&#30340;&#26368;&#22823;&#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>&#25351;&#21521;&#26032;&#20998;&#37197;&#30340;&#23383;&#31526;&#20018;&#30340;&#25351;&#38024;&#65292;&#25110;&#33509;&#20986;&#29616;&#38169;&#35823;&#21017;&#20026;&#31354;&#25351;&#38024;&#20540;&#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="http://pubs.opengroup.org/onlinepubs/9699919799/functions/strdup.html">POSIX strndup</a> &#65292;&#38500;&#20102;&#20801;&#35768;&#20294;&#19981;&#35201;&#27714;&#23427;&#22312;&#38169;&#35823;&#26102;&#35774;&#32622; <span class="t-lc"><a href="c-error-errno.html">errno</a></span> &#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;string.h&gt;</span>
<span class="co2">#include &lt;stdio.h&gt;</span>
<span class="co2">#include &lt;stdlib.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> <a href="c-types-size_t.html"><span class="kw100">size_t</span></a> n <span class="sy1">=</span> <span class="nu0">3</span><span class="sy4">;</span>
<span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>src <span class="sy1">=</span> <span class="st0">&quot;Replica&quot;</span><span class="sy4">;</span>
<span class="kw4">char</span> <span class="sy2">*</span>dup <span class="sy1">=</span> strndup<span class="br0">(</span>src, n<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;strndup(<span class="es1">\&quot;</span>%s<span class="es1">\&quot;</span>, %lu) == <span class="es1">\&quot;</span>%s<span class="es1">\&quot;</span><span class="es1">\n</span>&quot;</span>, src, n, dup<span class="br0">)</span><span class="sy4">;</span>
<a href="c-memory-free.html"><span class="kw406">free</span></a><span class="br0">(</span>dup<span class="br0">)</span><span class="sy4">;</span>
src <span class="sy1">=</span> <span class="st0">&quot;Hi&quot;</span><span class="sy4">;</span>
dup <span class="sy1">=</span> strndup<span class="br0">(</span>src, n<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;strndup(<span class="es1">\&quot;</span>%s<span class="es1">\&quot;</span>, %lu) == <span class="es1">\&quot;</span>%s<span class="es1">\&quot;</span><span class="es1">\n</span>&quot;</span>, src, n, dup<span class="br0">)</span><span class="sy4">;</span>
<a href="c-memory-free.html"><span class="kw406">free</span></a><span class="br0">(</span>dup<span class="br0">)</span><span class="sy4">;</span>
<span class="kw4">const</span> <span class="kw4">char</span> arr<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <span class="br0">{</span><span class="st0">&#39;A&#39;</span>,<span class="st0">&#39;B&#39;</span>,<span class="st0">&#39;C&#39;</span>,<span class="st0">&#39;D&#39;</span><span class="br0">}</span><span class="sy4">;</span> <span class="co1">// NB &#65306;&#26080;&#23614;&#38543; &#39;\0&#39;</span>
dup <span class="sy1">=</span> strndup<span class="br0">(</span>arr, n<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;strndup({&#39;A&#39;,&#39;B&#39;,&#39;C&#39;,&#39;D&#39;}, %lu) == <span class="es1">\&quot;</span>%s<span class="es1">\&quot;</span><span class="es1">\n</span>&quot;</span>, n, dup<span class="br0">)</span><span class="sy4">;</span>
<a href="c-memory-free.html"><span class="kw406">free</span></a><span class="br0">(</span>dup<span class="br0">)</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">strndup(&quot;Replica&quot;, 3) == &quot;Rep&quot;
strndup(&quot;Hi&quot;, 3) == &quot;Hi&quot;
strndup({&#39;A&#39;,&#39;B&#39;,&#39;C&#39;,&#39;D&#39;}, 3) == &quot;ABC&quot;</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="c-string-byte-strdup.html"><span class="t-lines"><span>strdup</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c23">(C23)</span></span></span></div>
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<td>&#20998;&#37197;&#23383;&#31526;&#20018;&#30340;&#21103;&#26412;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<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>
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<td>&#22797;&#21046;&#19968;&#20010;&#23383;&#31526;&#20018;&#32473;&#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="c-memory-malloc.html"><span class="t-lines"><span>malloc</span></span></a></div>
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<td>&#20998;&#37197;&#20869;&#23384;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<div class="t-dsc-member-div">
<div><a href="c-memory-free.html"><span class="t-lines"><span>free</span></span></a></div>
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<td>&#24402;&#36824;&#20043;&#21069;&#20998;&#37197;&#30340;&#20869;&#23384;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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