| | 1 | .\" $NetBSD: ungetwc.3,v 1.3 2002/02/07 07:00:27 ross Exp $ |
| | 2 | .\" |
| | 3 | .\" Copyright (c) 1990, 1991, 1993 |
| | 4 | .\" The Regents of the University of California. All rights reserved. |
| | 5 | .\" |
| | 6 | .\" This code is derived from software contributed to Berkeley by |
| | 7 | .\" Chris Torek and the American National Standards Committee X3, |
| | 8 | .\" on Information Processing Systems. |
| | 9 | .\" |
| | 10 | .\" Redistribution and use in source and binary forms, with or without |
| | 11 | .\" modification, are permitted provided that the following conditions |
| | 12 | .\" are met: |
| | 13 | .\" 1. Redistributions of source code must retain the above copyright |
| | 14 | .\" notice, this list of conditions and the following disclaimer. |
| | 15 | .\" 2. Redistributions in binary form must reproduce the above copyright |
| | 16 | .\" notice, this list of conditions and the following disclaimer in the |
| | 17 | .\" documentation and/or other materials provided with the distribution. |
| | 18 | .\" 4. Neither the name of the University nor the names of its contributors |
| | 19 | .\" may be used to endorse or promote products derived from this software |
| | 20 | .\" without specific prior written permission. |
| | 21 | .\" |
| | 22 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| | 23 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| | 24 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| | 25 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| | 26 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| | 27 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| | 28 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| | 29 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| | 30 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| | 31 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| | 32 | .\" SUCH DAMAGE. |
| | 33 | .\" |
| | 34 | .\" @(#)ungetc.3 8.1 (Berkeley) 6/4/93 |
| | 35 | .\" $FreeBSD: src/lib/libc/stdio/ungetwc.3,v 1.6 2007/01/09 00:28:07 imp Exp $ |
| | 36 | .\" |
| | 37 | .Dd March 3, 2004 |
| | 38 | .Dt UNGETWC 3 |
| | 39 | .Os |
| | 40 | .Sh NAME |
| | 41 | .Nm ungetwc , |
| | 42 | .Nm ungetwc_l |
| | 43 | .Nd un-get wide character from input stream |
| | 44 | .Sh LIBRARY |
| | 45 | .Lb libc |
| | 46 | .Sh SYNOPSIS |
| | 47 | .In stdio.h |
| | 48 | .In wchar.h |
| | 49 | .Ft wint_t |
| | 50 | .Fo ungetwc |
| | 51 | .Fa "wint_t wc" |
| | 52 | .Fa "FILE *stream" |
| | 53 | .Fc |
| | 54 | .In stdio.h |
| | 55 | .In wchar.h |
| | 56 | .In xlocale.h |
| | 57 | .Ft wint_t |
| | 58 | .Fo ungetwc_l |
| | 59 | .Fa "wint_t wc" |
| | 60 | .Fa "FILE *stream" |
| | 61 | .Fa "locale_t loc" |
| | 62 | .Fc |
| | 63 | .Sh DESCRIPTION |
| | 64 | The |
| | 65 | .Fn ungetwc |
| | 66 | function pushes the wide character |
| | 67 | .Fa wc |
| | 68 | (converted to an |
| | 69 | .Vt wchar_t ) |
| | 70 | back onto the input stream pointed to by |
| | 71 | .Fa stream . |
| | 72 | The pushed-backed wide characters will be returned (in reverse order) |
| | 73 | by subsequent reads on the stream. |
| | 74 | A successful intervening call to one of the file |
| | 75 | positioning functions |
| | 76 | .Xr fseek 3 , |
| | 77 | .Xr fsetpos 3 , |
| | 78 | or |
| | 79 | .Xr rewind 3 , |
| | 80 | using the same stream, |
| | 81 | will discard the pushed-back wide characters. |
| | 82 | .Pp |
| | 83 | Only one wide character of push-back is guaranteed, |
| | 84 | but as long as there is sufficient memory, |
| | 85 | an effectively infinite amount of push-back is allowed. |
| | 86 | .Pp |
| | 87 | If a character is successfully pushed-back, |
| | 88 | the end-of-file indicator for the stream is cleared. |
| | 89 | .Pp |
| | 90 | Although the |
| | 91 | .Fn ungetwc |
| | 92 | function uses the current locale, the |
| | 93 | .Fn ungetwc_l |
| | 94 | function may be passed a locale directly. See |
| | 95 | .Xr xlocale 3 |
| | 96 | for more information. |
| | 97 | .Sh RETURN VALUES |
| | 98 | The |
| | 99 | .Fn ungetwc |
| | 100 | function |
| | 101 | returns |
| | 102 | the wide character pushed-back after the conversion, or |
| | 103 | .Dv WEOF |
| | 104 | if the operation fails. |
| | 105 | If the value of the argument |
| | 106 | .Fa c |
| | 107 | character equals |
| | 108 | .Dv WEOF , |
| | 109 | the operation will fail and the stream will remain unchanged. |
| | 110 | .Sh SEE ALSO |
| | 111 | .Xr fseek 3 , |
| | 112 | .Xr getwc 3 , |
| | 113 | .Xr xlocale 3 |
| | 114 | .Sh STANDARDS |
| | 115 | The |
| | 116 | .Fn ungetwc |
| | 117 | function conforms to |
| | 118 | .St -isoC-99 . |
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