151 lines
6.3 KiB
HTML
151 lines
6.3 KiB
HTML
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<title>mbtowc</title>
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<basefont size="3"> <a name="mbtowc"></a> <a name="tag_03_364"></a><!-- mbtowc -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_03_364_01"></a>NAME</h4>
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<blockquote>mbtowc - convert a character to a wide-character code</blockquote>
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<h4><a name="tag_03_364_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>#include <<a href="../basedefs/stdlib.h.html">stdlib.h</a>><br>
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<br>
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int mbtowc(wchar_t *restrict</tt> <i>pwc</i><tt>, const char *restrict</tt> <i>s</i><tt>, size_t</tt> <i>n</i><tt>);<br>
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</tt></code></p>
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</blockquote>
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<h4><a name="tag_03_364_03"></a>DESCRIPTION</h4>
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<blockquote>
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<div class="box"><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]"
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border="0"> The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the
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requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to
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the ISO C standard. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></div>
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<p>If <i>s</i> is not a null pointer, <i>mbtowc</i>() shall determine the number of bytes that constitute the character pointed to
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by <i>s</i>. It shall then determine the wide-character code for the value of type <b>wchar_t</b> that corresponds to that
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character. (The value of the wide-character code corresponding to the null byte is 0.) If the character is valid and <i>pwc</i> is
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not a null pointer, <i>mbtowc</i>() shall store the wide-character code in the object pointed to by <i>pwc</i>.</p>
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<p>The behavior of this function is affected by the <i>LC_CTYPE</i> category of the current locale. For a state-dependent encoding,
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this function is placed into its initial state by a call for which its character pointer argument, <i>s</i>, is a null pointer.
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Subsequent calls with <i>s</i> as other than a null pointer shall cause the internal state of the function to be altered as
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necessary. A call with <i>s</i> as a null pointer shall cause this function to return a non-zero value if encodings have state
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dependency, and 0 otherwise. If the implementation employs special bytes to change the shift state, these bytes shall not produce
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separate wide-character codes, but shall be grouped with an adjacent character. Changing the <i>LC_CTYPE</i> category causes the
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shift state of this function to be unspecified. At most <i>n</i> bytes of the array pointed to by <i>s</i> shall be examined.</p>
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<p>The implementation shall behave as if no function defined in this volume of IEEE Std 1003.1-2001 calls
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<i>mbtowc</i>().</p>
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</blockquote>
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<h4><a name="tag_03_364_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>If <i>s</i> is a null pointer, <i>mbtowc</i>() shall return a non-zero or 0 value, if character encodings, respectively, do or
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do not have state-dependent encodings. If <i>s</i> is not a null pointer, <i>mbtowc</i>() shall either return 0 (if <i>s</i> points
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to the null byte), or return the number of bytes that constitute the converted character (if the next <i>n</i> or fewer bytes form
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a valid character), or return -1 <sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> and may set <i>errno</i> to indicate the error <img src="../images/opt-end.gif" alt=
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"[Option End]" border="0"> (if they do not form a valid character).</p>
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<p>In no case shall the value returned be greater than <i>n</i> or the value of the {MB_CUR_MAX} macro.</p>
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</blockquote>
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<h4><a name="tag_03_364_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>mbtowc</i>() function may fail if:</p>
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<dl compact>
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<dt>[EILSEQ]</dt>
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<dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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Invalid character sequence is detected. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>
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</dl>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_03_364_06"></a>EXAMPLES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_364_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_364_08"></a>RATIONALE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_364_09"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_364_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="mblen.html"><i>mblen</i>()</a> , <a href="mbstowcs.html"><i>mbstowcs</i>()</a> , <a href=
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"wctomb.html"><i>wctomb</i>()</a> , <a href="wcstombs.html"><i>wcstombs</i>()</a> , the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/stdlib.h.html"><i><stdlib.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_364_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 4. Aligned with the ISO C standard.</p>
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</blockquote>
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<h4><a name="tag_03_364_12"></a>Issue 6</h4>
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<blockquote>
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<p>The <i>mbtowc</i>() prototype is updated for alignment with the ISO/IEC 9899:1999 standard.</p>
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<p>Extensions beyond the ISO C standard are marked.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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