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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>ungetwc</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_000_010_265"> </a>NAME</h4><blockquote>ungetwc - push wide-character code back into input stream</blockquote><h4><a name = "tag_000_010_266"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="stdio.h.html">stdio.h</a>>#include <<a href="wchar.h.html">wchar.h</a>>wint_t ungetwc(wint_t <i>wc</i>, FILE *<i>stream</i>);</code></pre></blockquote><h4><a name = "tag_000_010_267"> </a>DESCRIPTION</h4><blockquote>The<i>ungetwc()</i>function pushes the character corresponding to the wide-character codespecified by<i>wc</i>back onto the input stream pointed to by<i>stream</i>.The pushed-back characters will be returned by subsequent readson that stream in the reverse order of their pushing.A successful intervening call (with the stream pointed to by<i>stream</i>)to a file-positioning function (.Fn fseek ,<i><a href="fsetpos.html">fsetpos()</a></i>or<i><a href="rewind.html">rewind()</a></i>)discards any pushed-back characters for the stream.The external storage corresponding to the stream is unchanged.<p>One character of push-back is guaranteed.If<i>ungetwc()</i>is called too many times on the same stream without an intervening read orfile-positioning operation on that stream, the operation may fail.<p>If the value of<i>wc</i>equals that of the macro WEOF, the operation fails and the inputstream is unchanged.<p>A successful call to<i>ungetwc()</i>clears the end-of-file indicator for the stream.The value of the file-position indicator for the stream afterreading or discarding all pushed-back characters will be the sameas it was before the characters were pushed back.The file-position indicator is decremented (by one or more) by each successfulcall to<i>ungetwc()</i>;if its value was 0 before a call, its value is indeterminate after the call.</blockquote><h4><a name = "tag_000_010_268"> </a>RETURN VALUE</h4><blockquote>Upon successful completion,<i>ungetwc()</i>returns the wide-character code corresponding to thepushed-back character.Otherwise it returns WEOF.</blockquote><h4><a name = "tag_000_010_269"> </a>ERRORS</h4><blockquote>The<i>ungetwc()</i>function may fail if:<dl compact><dt>[EILSEQ]<dd>An invalid character sequence is detected, or a wide-character code does notcorrespond to a valid character.</dl></blockquote><h4><a name = "tag_000_010_270"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_010_271"> </a>APPLICATION USAGE</h4><blockquote>None.</blockquote><h4><a name = "tag_000_010_272"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_010_273"> </a>SEE ALSO</h4><blockquote><i><a href="fseek.html">fseek()</a></i>,<i><a href="fsetpos.html">fsetpos()</a></i>,<i><a href="read.html">read()</a></i>,<i><a href="rewind.html">rewind()</a></i>,<i><a href="setbuf.html">setbuf()</a></i>,<i><a href="stdio.h.html"><stdio.h></a></i>,<i><a href="wchar.h.html"><wchar.h></a></i>.</blockquote><h4>DERIVATION</h4><blockquote>Derived from the MSE working draft.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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