1*2fe8fb19SBen Gras.\" $NetBSD: ungetwc.3,v 1.8 2010/12/16 17:42:27 wiz Exp $ 2*2fe8fb19SBen Gras.\" 3*2fe8fb19SBen Gras.\" Copyright (c) 1990, 1991, 1993 4*2fe8fb19SBen Gras.\" The Regents of the University of California. All rights reserved. 5*2fe8fb19SBen Gras.\" 6*2fe8fb19SBen Gras.\" This code is derived from software contributed to Berkeley by 7*2fe8fb19SBen Gras.\" Chris Torek and the American National Standards Committee X3, 8*2fe8fb19SBen Gras.\" on Information Processing Systems. 9*2fe8fb19SBen Gras.\" 10*2fe8fb19SBen Gras.\" Redistribution and use in source and binary forms, with or without 11*2fe8fb19SBen Gras.\" modification, are permitted provided that the following conditions 12*2fe8fb19SBen Gras.\" are met: 13*2fe8fb19SBen Gras.\" 1. Redistributions of source code must retain the above copyright 14*2fe8fb19SBen Gras.\" notice, this list of conditions and the following disclaimer. 15*2fe8fb19SBen Gras.\" 2. Redistributions in binary form must reproduce the above copyright 16*2fe8fb19SBen Gras.\" notice, this list of conditions and the following disclaimer in the 17*2fe8fb19SBen Gras.\" documentation and/or other materials provided with the distribution. 18*2fe8fb19SBen Gras.\" 3. Neither the name of the University nor the names of its contributors 19*2fe8fb19SBen Gras.\" may be used to endorse or promote products derived from this software 20*2fe8fb19SBen Gras.\" without specific prior written permission. 21*2fe8fb19SBen Gras.\" 22*2fe8fb19SBen Gras.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23*2fe8fb19SBen Gras.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24*2fe8fb19SBen Gras.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25*2fe8fb19SBen Gras.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26*2fe8fb19SBen Gras.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27*2fe8fb19SBen Gras.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28*2fe8fb19SBen Gras.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29*2fe8fb19SBen Gras.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30*2fe8fb19SBen Gras.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31*2fe8fb19SBen Gras.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32*2fe8fb19SBen Gras.\" SUCH DAMAGE. 33*2fe8fb19SBen Gras.\" 34*2fe8fb19SBen Gras.\" @(#)ungetc.3 8.1 (Berkeley) 6/4/93 35*2fe8fb19SBen Gras.\" 36*2fe8fb19SBen Gras.Dd October 24, 2001 37*2fe8fb19SBen Gras.Dt UNGETWC 3 38*2fe8fb19SBen Gras.Os 39*2fe8fb19SBen Gras.Sh NAME 40*2fe8fb19SBen Gras.Nm ungetwc 41*2fe8fb19SBen Gras.Nd un-get wide character from input stream 42*2fe8fb19SBen Gras.Sh LIBRARY 43*2fe8fb19SBen Gras.Lb libc 44*2fe8fb19SBen Gras.Sh SYNOPSIS 45*2fe8fb19SBen Gras.In stdio.h 46*2fe8fb19SBen Gras.In wchar.h 47*2fe8fb19SBen Gras.Ft wint_t 48*2fe8fb19SBen Gras.Fn ungetwc "wint_t wc" "FILE *stream" 49*2fe8fb19SBen Gras.Sh DESCRIPTION 50*2fe8fb19SBen GrasThe 51*2fe8fb19SBen Gras.Fn ungetwc 52*2fe8fb19SBen Grasfunction pushes the wide character 53*2fe8fb19SBen Gras.Fa wc 54*2fe8fb19SBen Gras(converted to an wchar_t) 55*2fe8fb19SBen Grasback onto the input stream pointed to by 56*2fe8fb19SBen Gras.Fa stream . 57*2fe8fb19SBen GrasThe pushed-backed wide characters will be returned by subsequent reads on the 58*2fe8fb19SBen Grasstream (in reverse order). 59*2fe8fb19SBen GrasA successful intervening call, using the same stream, to one of the file 60*2fe8fb19SBen Graspositioning functions 61*2fe8fb19SBen Gras.Xr fseek 3 , 62*2fe8fb19SBen Gras.Xr fsetpos 3 , 63*2fe8fb19SBen Grasor 64*2fe8fb19SBen Gras.Xr rewind 3 65*2fe8fb19SBen Graswill discard the pushed back wide characters. 66*2fe8fb19SBen Gras.Pp 67*2fe8fb19SBen GrasOne wide character of push-back is guaranteed, 68*2fe8fb19SBen Grasbut as long as there is 69*2fe8fb19SBen Grassufficient memory, an effectively infinite amount of pushback is allowed. 70*2fe8fb19SBen Gras.Pp 71*2fe8fb19SBen GrasIf a character is successfully pushed-back, 72*2fe8fb19SBen Grasthe end-of-file indicator for the stream is cleared. 73*2fe8fb19SBen Gras.Sh RETURN VALUES 74*2fe8fb19SBen GrasThe 75*2fe8fb19SBen Gras.Fn ungetwc 76*2fe8fb19SBen Grasfunction 77*2fe8fb19SBen Grasreturns 78*2fe8fb19SBen Grasthe wide character pushed-back after the conversion, or 79*2fe8fb19SBen Gras.Dv WEOF 80*2fe8fb19SBen Grasif the operation fails. 81*2fe8fb19SBen GrasIf the value of the argument 82*2fe8fb19SBen Gras.Fa c 83*2fe8fb19SBen Grascharacter equals 84*2fe8fb19SBen Gras.Dv WEOF , 85*2fe8fb19SBen Grasthe operation will fail and the stream will remain unchanged. 86*2fe8fb19SBen Gras.Sh SEE ALSO 87*2fe8fb19SBen Gras.Xr fseek 3 , 88*2fe8fb19SBen Gras.Xr getwc 3 89*2fe8fb19SBen Gras.Sh STANDARDS 90*2fe8fb19SBen GrasThe 91*2fe8fb19SBen Gras.Fn ungetwc 92*2fe8fb19SBen Grasfunction conforms to 93*2fe8fb19SBen Gras.St -isoC-99 . 94*2fe8fb19SBen Gras.Sh BUGS 95*2fe8fb19SBen GrasThe current implementation uses a fixed sized ungetwc-buffer. 96