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<a name="mbtowc_002d_002d_002dminimal-multibyte-to-wide-char-converter"></a>
<h3 class="section">2.30 <code>mbtowc</code>&mdash;minimal multibyte to wide char converter</h3>
<a name="index-mbtowc"></a>
<p><strong>Synopsis</strong>
</p><div class="example">
<pre class="example">#include &lt;stdlib.h&gt;
int mbtowc(wchar_t *restrict <var>pwc</var>, const char *restrict <var>s</var>, size_t <var>n</var>);

</pre></div>
<p><strong>Description</strong><br>
When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming 
implementation of <code>mbtowc</code>.  In this case,
only &ldquo;multi-byte character sequences&rdquo; recognized are single bytes,
and they are &ldquo;converted&rdquo; to themselves.
Each call to <code>mbtowc</code> copies one character from <code>*<var>s</var></code> to
<code>*<var>pwc</var></code>, unless <var>s</var> is a null pointer.  The argument n
is ignored.
</p>
<p>When _MB_CAPABLE is defined, this routine calls <code>_mbtowc_r</code> to perform
the conversion, passing a state variable to allow state dependent
decoding.  The result is based on the locale setting which may
be restricted to a defined set of locales.
</p>
<br>
<p><strong>Returns</strong><br>
This implementation of <code>mbtowc</code> returns <code>0</code> if
<var>s</var> is <code>NULL</code> or is the empty string; 
it returns <code>1</code> if not _MB_CAPABLE or
the character is a single-byte character; it returns <code>-1</code>
if n is <code>0</code> or the multi-byte character is invalid; 
otherwise it returns the number of bytes in the multibyte character.
If the return value is -1, no changes are made to the <code>pwc</code>
output string.  If the input is the empty string, a wchar_t nul
is placed in the output string and 0 is returned.  If the input
has a length of 0, no changes are made to the <code>pwc</code> output string.
</p>
<br>
<p><strong>Portability</strong><br>
<code>mbtowc</code> is required in the ANSI C standard.  However, the precise
effects vary with the locale.
</p>
<p><code>mbtowc</code> requires no supporting OS subroutines.
</p>
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