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<td> <div>Defined in header <code><string.h></code>
</div></td>
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<td></td>
</tr>
<tr class="t-dcl">
<td> <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>str, <a href="../../types/size_t.html"><span class="kw100">size_t</span></a> size<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-dynamic-tr t-mark-ts">(dynamic memory TR)</span> </td>
</tr>
<tr class="t-dcl-sep"><td></td><td></td><td></td></tr>
</tbody></table>
<p>Returns a pointer to a null-terminated byte string, which contains copies of at most <code>size</code> bytes from the string pointed to by <code>str</code>. If the null terminator is not encountered in the first <code>size</code> bytes, it is added to the duplicated string.
</p><p>The returned pointer must be passed to <span class="t-lc"><a href="../../memory/free.html" title="c/memory/free">free</a></span> to avoid a memory leak.
</p><p>If an error occurs, a null pointer is returned and <span class="t-lc"><a href="../../error/errno.html" title="c/error/errno">errno</a></span> may be set.
</p><p>As all functions from Dynamic Memory TS, <code>strndup</code> is only guaranteed to be available if <span class="t-c"><span class="mw-geshi c source-c">__STDC_ALLOC_LIB__</span></span> is defined by the implementation and if the user defines <span class="t-c"><span class="mw-geshi c source-c">__STDC_WANT_LIB_EXT2__</span></span> to the integer constant <span class="t-c"><span class="mw-geshi c source-c"><span class="nu0">1</span></span></span> before including <code>string.h</code>.
</p>
<table id="toc" class="toc"><tr><td><div id="toctitle"><h2>Contents</h2></div>
<ul>
<li class="toclevel-1 tocsection-1"><a href="strndup.html#Parameters"><span class="tocnumber">1</span> <span class="toctext">Parameters</span></a></li>
<li class="toclevel-1 tocsection-2"><a href="strndup.html#Return_value"><span class="tocnumber">2</span> <span class="toctext">Return value</span></a></li>
<li class="toclevel-1 tocsection-3"><a href="strndup.html#Notes"><span class="tocnumber">3</span> <span class="toctext">Notes</span></a></li>
<li class="toclevel-1 tocsection-4"><a href="strndup.html#Example"><span class="tocnumber">4</span> <span class="toctext">Example</span></a></li>
<li class="toclevel-1 tocsection-5"><a href="strndup.html#See_also"><span class="tocnumber">5</span> <span class="toctext">See also</span></a></li>
</ul>
</td></tr></table>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=c/experimental/dynamic/strndup&action=edit&section=1" title="Edit section: Parameters">edit</a>]</span> <span class="mw-headline" id="Parameters">Parameters</span></h3>
<table class="t-par-begin">
<tr class="t-par">
<td> str
</td>
<td> -
</td>
<td> pointer to the null-terminated byte string to duplicate
</td></tr>
<tr class="t-par">
<td> size
</td>
<td> -
</td>
<td> max number of bytes to copy from <code>str</code>
</td></tr></table>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=c/experimental/dynamic/strndup&action=edit&section=2" title="Edit section: Return value">edit</a>]</span> <span class="mw-headline" id="Return_value">Return value</span></h3>
<p>A pointer to the newly allocated string, or a null pointer if an error occurred.
</p>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=c/experimental/dynamic/strndup&action=edit&section=3" title="Edit section: Notes">edit</a>]</span> <span class="mw-headline" id="Notes">Notes</span></h3>
<p>The function is identical to the <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/strdup.html">POSIX strndup</a> except that it is allowed, but not required to set <span class="t-lc"><a href="../../error/errno.html" title="c/error/errno">errno</a></span> on error.
</p>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=c/experimental/dynamic/strndup&action=edit&section=4" title="Edit section: Example">edit</a>]</span> <span class="mw-headline" id="Example">Example</span></h3>
<div class="t-example"><div class="t-example-live-link"><div class="coliru-btn coliru-btn-run-init">Run this code</div></div>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="c source-c"><pre class="de1"><span class="co2">#define __STDC_WANT_LIB_EXT2__ 1</span>
<span class="co2">#include <string.h></span>
<span class="co2">#include <stdio.h></span>
<span class="co2">#include <stdlib.h></span>
 
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw4">char</span> <span class="sy2">*</span>s1 <span class="sy1">=</span> <span class="st0">"String"</span><span class="sy4">;</span>
<span class="kw4">char</span> <span class="sy2">*</span>s2 <span class="sy1">=</span> strndup<span class="br0">(</span>s1, <span class="nu0">2</span><span class="br0">)</span><span class="sy4">;</span>
<a href="../../io/fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"strndup(<span class="es1">\"</span>String<span class="es1">\"</span>, 2) == %s<span class="es1">\n</span>"</span>, s2<span class="br0">)</span><span class="sy4">;</span>
<a href="../../memory/free.html"><span class="kw406">free</span></a><span class="br0">(</span>s2<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div></div>
<p>Output:
</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="text source-text"><pre class="de1">strndup("String", 2) == St</pre></div></div>
</div>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=c/experimental/dynamic/strndup&action=edit&section=5" title="Edit section: See also">edit</a>]</span> <span class="mw-headline" id="See_also">See also</span></h3>
<table class="t-dsc-begin">
<tr class="t-dsc">
<td> <div class="t-dsc-member-div"><div><a href="strdup.html" title="c/experimental/dynamic/strdup"> <span class="t-lines"><span>strdup</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-dynamic-tr t-mark-ts">(dynamic memory TR)</span></span></span></div></div>
</td>
<td> allocate a copy of a string <br /> <span class="t-mark">(function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:c/experimental/dynamic/dsc_strdup&action=edit">[edit]</a></span>
</td></tr>
<tr class="t-dsc">
<td> <div class="t-dsc-member-div"><div><a href="../../string/byte/strncpy.html" title="c/string/byte/strncpy"> <span class="t-lines"><span>strncpy</span><span>strncpy_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> copies a certain amount of characters from one string to another <br /> <span class="t-mark">(function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:c/string/byte/dsc_strncpy&action=edit">[edit]</a></span>
</td></tr>
<tr class="t-dsc">
<td> <div class="t-dsc-member-div"><div><a href="../../memory/malloc.html" title="c/memory/malloc"> <span class="t-lines"><span>malloc</span></span></a></div></div>
</td>
<td> allocates memory <br /> <span class="t-mark">(function)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:c/memory/dsc_malloc&action=edit">[edit]</a></span>
</td></tr>
</table>
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