216 lines
9.2 KiB
HTML
216 lines
9.2 KiB
HTML
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<title>fgetwc</title>
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<basefont size="3"> <a name="fgetwc"></a> <a name="tag_03_165"></a><!-- fgetwc -->
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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_165_01"></a>NAME</h4>
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<blockquote>fgetwc - get a wide-character code from a stream</blockquote>
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<h4><a name="tag_03_165_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>#include <<a href="../basedefs/stdio.h.html">stdio.h</a>><br>
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#include <<a href="../basedefs/wchar.h.html">wchar.h</a>><br>
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<br>
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wint_t fgetwc(FILE *</tt><i>stream</i><tt>);<br>
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</tt></code></p>
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</blockquote>
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<h4><a name="tag_03_165_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>The <i>fgetwc</i>() function shall obtain the next character (if present) from the input stream pointed to by <i>stream</i>,
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convert that to the corresponding wide-character code, and advance the associated file position indicator for the stream (if
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defined).</p>
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<p>If an error occurs, the resulting value of the file position indicator for the stream is unspecified.</p>
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<p><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> The
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<i>fgetwc</i>() function may mark the <i>st_atime</i> field of the file associated with <i>stream</i> for update. The
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<i>st_atime</i> field shall be marked for update by the first successful execution of <a href=
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"../functions/fgetc.html"><i>fgetc</i>()</a>, <a href="../functions/fgets.html"><i>fgets</i>()</a>, <i>fgetwc</i>(), <a href=
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"../functions/fgetws.html"><i>fgetws</i>()</a>, <a href="../functions/fread.html"><i>fread</i>()</a>, <a href=
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"../functions/fscanf.html"><i>fscanf</i>()</a>, <a href="../functions/getc.html"><i>getc</i>()</a>, <a href=
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"../functions/getchar.html"><i>getchar</i>()</a>, <a href="../functions/gets.html"><i>gets</i>()</a>, or <a href=
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"../functions/scanf.html"><i>scanf</i>()</a> using <i>stream</i> that returns data not supplied by a prior call to <a href=
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"../functions/ungetc.html"><i>ungetc</i>()</a> or <a href="../functions/ungetwc.html"><i>ungetwc</i>()</a>. <img src=
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"../images/opt-end.gif" alt="[Option End]" border="0"></p>
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</blockquote>
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<h4><a name="tag_03_165_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, the <i>fgetwc</i>() function shall return the wide-character code of the character read from the
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input stream pointed to by <i>stream</i> converted to a type <b>wint_t</b>. If the stream is at end-of-file, the end-of-file
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indicator for the stream shall be set and <i>fgetwc</i>() shall return WEOF. If a read error occurs, the error indicator for the
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stream shall be set, <i>fgetwc</i>() shall return WEOF, <sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src=
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"../images/opt-start.gif" alt="[Option Start]" border="0"> and shall set <i>errno</i> to indicate the error. <img src=
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"../images/opt-end.gif" alt="[Option End]" border="0"> If an encoding error occurs, the error indicator for the stream shall be
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set, <i>fgetwc</i>() shall return WEOF, and shall set <i>errno</i> to indicate the error.</p>
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</blockquote>
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<h4><a name="tag_03_165_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>fgetwc</i>() function shall fail if data needs to be read and:</p>
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<dl compact>
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<dt>[EAGAIN]</dt>
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<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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The O_NONBLOCK flag is set for the file descriptor underlying <i>stream</i> and the process would be delayed in the <i>fgetwc</i>()
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operation. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>
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<dt>[EBADF]</dt>
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<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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The file descriptor underlying <i>stream</i> is not a valid file descriptor open for reading. <img src="../images/opt-end.gif" alt=
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"[Option End]" border="0"></dd>
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<dt>[EILSEQ]</dt>
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<dd>The data obtained from the input stream does not form a valid character.</dd>
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<dt>[EINTR]</dt>
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<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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The read operation was terminated due to the receipt of a signal, and no data was transferred. <img src="../images/opt-end.gif"
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alt="[Option End]" border="0"></dd>
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<dt>[EIO]</dt>
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<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> A
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physical I/O error has occurred, or the process is in a background process group attempting to read from its controlling terminal,
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and either the process is ignoring or blocking the SIGTTIN signal or the process group is orphaned. This error may also be
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generated for implementation-defined reasons. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>
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<dt>[EOVERFLOW]</dt>
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<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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The file is a regular file and an attempt was made to read at or beyond the offset maximum associated with the corresponding
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stream. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>
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</dl>
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<p>The <i>fgetwc</i>() function may fail if:</p>
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<dl compact>
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<dt>[ENOMEM]</dt>
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<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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Insufficient storage space is available. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>
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<dt>[ENXIO]</dt>
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<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> A
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request was made of a nonexistent device, or the request was outside the capabilities of the device. <img src=
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"../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_165_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_165_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>The <a href="../functions/ferror.html"><i>ferror</i>()</a> or <a href="../functions/feof.html"><i>feof</i>()</a> functions must
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be used to distinguish between an error condition and an end-of-file condition.</p>
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</blockquote>
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<h4><a name="tag_03_165_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_165_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_165_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="feof.html"><i>feof</i>()</a> , <a href="ferror.html"><i>ferror</i>()</a> , <a href="fopen.html"><i>fopen</i>()</a> ,
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the Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/stdio.h.html"><i><stdio.h></i></a>, <a
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href="../basedefs/wchar.h.html"><i><wchar.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_165_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 4. Derived from the MSE working draft.</p>
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</blockquote>
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<h4><a name="tag_03_165_12"></a>Issue 5</h4>
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<blockquote>
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<p>The Optional Header (OH) marking is removed from <a href="../basedefs/stdio.h.html"><i><stdio.h></i></a>.</p>
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<p>Large File Summit extensions are added.</p>
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</blockquote>
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<h4><a name="tag_03_165_13"></a>Issue 6</h4>
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<blockquote>
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<p>Extensions beyond the ISO C standard are marked.</p>
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<p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p>
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<ul>
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<li>
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<p>The [EIO] and [EOVERFLOW] mandatory error conditions are added.</p>
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</li>
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<li>
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<p>The [ENOMEM] and [ENXIO] optional error conditions are added.</p>
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</li>
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</ul>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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<hr>
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<hr size="2" noshade>
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<center><font size="2"><!--footer start-->
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UNIX ® is a registered Trademark of The Open Group.<br>
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POSIX ® is a registered Trademark of The IEEE.<br>
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[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href=
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"../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>
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