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<a name="mbstowcs_002d_002d_002dminimal-multibyte-string-to-wide-char-converter"></a>
<h3 class="section">2.29 <code>mbstowcs</code>&mdash;minimal multibyte string to wide char converter</h3>
<a name="index-mbstowcs"></a>
<p><strong>Synopsis</strong>
</p><div class="example">
<pre class="example">#include &lt;stdlib.h&gt;
int mbstowcs(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>mbstowcs</code>.  In this case, the
only &ldquo;multi-byte character sequences&rdquo; recognized are single bytes,
and they are &ldquo;converted&rdquo; to wide-char versions simply by byte
extension.
</p>
<p>When _MB_CAPABLE is defined, this routine calls <code>_mbstowcs_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>mbstowcs</code> returns <code>0</code> if
<var>s</var> is <code>NULL</code> or is the empty string; 
it returns <code>-1</code> if _MB_CAPABLE and one of the
multi-byte characters is invalid or incomplete;
otherwise it returns the minimum of: <code>n</code> or the
number of multi-byte characters in <code>s</code> plus 1 (to
compensate for the nul character).
If the return value is -1, the state of the <code>pwc</code> string is
indeterminate.  If the input has a length of 0, the output
string will be modified to contain a wchar_t nul terminator.
</p>
<br>
<p><strong>Portability</strong><br>
<code>mbstowcs</code> is required in the ANSI C standard.  However, the precise
effects vary with the locale.
</p>
<p><code>mbstowcs</code> requires no supporting OS subroutines.
</p>
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