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<basefont size="3"> <a name="wcrtomb"></a> <a name="tag_03_825"></a><!-- wcrtomb -->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
IEEE Std 1003.1-2001<br>
Copyright &copy; 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<hr size="2" noshade>
<h4><a name="tag_03_825_01"></a>NAME</h4>
<blockquote>wcrtomb - convert a wide-character code to a character (restartable)</blockquote>
<h4><a name="tag_03_825_02"></a>SYNOPSIS</h4>
<blockquote class="synopsis">
<p><code><tt>#include &lt;<a href="../basedefs/stdio.h.html">stdio.h</a>&gt;<br>
<br>
size_t wcrtomb(char *restrict</tt> <i>s</i><tt>, wchar_t</tt> <i>wc</i><tt>, mbstate_t *restrict</tt> <i>ps</i><tt>);<br>
</tt></code></p>
</blockquote>
<h4><a name="tag_03_825_03"></a>DESCRIPTION</h4>
<blockquote>
<div class="box"><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]"
border="0"> The functionality described on this reference page is aligned with the ISO&nbsp;C standard. Any conflict between the
requirements described here and the ISO&nbsp;C standard is unintentional. This volume of IEEE&nbsp;Std&nbsp;1003.1-2001 defers to
the ISO&nbsp;C standard. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></div>
<p>If <i>s</i> is a null pointer, the <i>wcrtomb</i>() function shall be equivalent to the call:</p>
<pre>
<tt>wcrtomb(</tt><i>buf</i><tt>, L'\0',</tt> <i>ps</i><tt>)
</tt>
</pre>
<p>where <i>buf</i> is an internal buffer.</p>
<p>If <i>s</i> is not a null pointer, the <i>wcrtomb</i>() function shall determine the number of bytes needed to represent the
character that corresponds to the wide character given by <i>wc</i> (including any shift sequences), and store the resulting bytes
in the array whose first element is pointed to by <i>s</i>. At most {MB_CUR_MAX} bytes are stored. If <i>wc</i> is a null wide
character, a null byte shall be stored, preceded by any shift sequence needed to restore the initial shift state. The resulting
state described shall be the initial conversion state.</p>
<p>If <i>ps</i> is a null pointer, the <i>wcrtomb</i>() function shall use its own internal <b>mbstate_t</b> object, which is
initialized at program start-up to the initial conversion state. Otherwise, the <b>mbstate_t</b> object pointed to by <i>ps</i>
shall be used to completely describe the current conversion state of the associated character sequence. The implementation shall
behave as if no function defined in this volume of IEEE&nbsp;Std&nbsp;1003.1-2001 calls <i>wcrtomb</i>().</p>
<p><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> If
the application uses any of the _POSIX_THREAD_SAFE_FUNCTIONS or _POSIX_THREADS functions, the application shall ensure that the
<i>wcrtomb</i>() function is called with a non-NULL <i>ps</i> argument. <img src="../images/opt-end.gif" alt="[Option End]" border=
"0"></p>
<p>The behavior of this function shall be affected by the <i>LC_CTYPE</i> category of the current locale.</p>
</blockquote>
<h4><a name="tag_03_825_04"></a>RETURN VALUE</h4>
<blockquote>
<p>The <i>wcrtomb</i>() function shall return the number of bytes stored in the array object (including any shift sequences). When
<i>wc</i> is not a valid wide character, an encoding error shall occur. In this case, the function shall store the value of the
macro [EILSEQ] in <i>errno</i> and shall return (<b>size_t</b>)-1; the conversion state shall be undefined.</p>
</blockquote>
<h4><a name="tag_03_825_05"></a>ERRORS</h4>
<blockquote>
<p>The <i>wcrtomb</i>() function may fail if:</p>
<dl compact>
<dt>[EINVAL]</dt>
<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
<i>ps</i> points to an object that contains an invalid conversion state. <img src="../images/opt-end.gif" alt="[Option End]"
border="0"></dd>
<dt>[EILSEQ]</dt>
<dd>Invalid wide-character code is detected.</dd>
</dl>
</blockquote>
<hr>
<div class="box"><em>The following sections are informative.</em></div>
<h4><a name="tag_03_825_06"></a>EXAMPLES</h4>
<blockquote>
<p>None.</p>
</blockquote>
<h4><a name="tag_03_825_07"></a>APPLICATION USAGE</h4>
<blockquote>
<p>None.</p>
</blockquote>
<h4><a name="tag_03_825_08"></a>RATIONALE</h4>
<blockquote>
<p>None.</p>
</blockquote>
<h4><a name="tag_03_825_09"></a>FUTURE DIRECTIONS</h4>
<blockquote>
<p>None.</p>
</blockquote>
<h4><a name="tag_03_825_10"></a>SEE ALSO</h4>
<blockquote>
<p><a href="mbsinit.html"><i>mbsinit</i>()</a> , the Base Definitions volume of IEEE&nbsp;Std&nbsp;1003.1-2001, <a href=
"../basedefs/wchar.h.html"><i>&lt;wchar.h&gt;</i></a></p>
</blockquote>
<h4><a name="tag_03_825_11"></a>CHANGE HISTORY</h4>
<blockquote>
<p>First released in Issue 5. Included for alignment with ISO/IEC&nbsp;9899:1990/Amendment 1:1995 (E).</p>
</blockquote>
<h4><a name="tag_03_825_12"></a>Issue 6</h4>
<blockquote>
<p>In the DESCRIPTION, a note on using this function in a threaded application is added.</p>
<p>Extensions beyond the ISO&nbsp;C standard are marked.</p>
<p>The DESCRIPTION is updated to avoid use of the term &quot;must&quot; for application requirements.</p>
<p>The <i>wcrtomb</i>() prototype is updated for alignment with the ISO/IEC&nbsp;9899:1999 standard.</p>
</blockquote>
<div class="box"><em>End of informative text.</em></div>
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