usr/src/lib/libc/stdio/ungetc.3

.\" Copyright (c) 1990 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)ungetc.3    6.3 (Berkeley) %G%
.\"
.TH UNGETC 3 ""
.UC 7
.SH NAME
ungetc \- push character back into input stream
.SH SYNOPSIS
.nf
.ft B
#include <stdio.h>

int
ungetc(int c, FILE *stream);
.fr R
.fi
.SH DESCRIPTION
.I Ungetc
pushes the integer
.I c
(converted to an ``unsigned char'') back on an input stream, so that
the next
.I getc
call on that stream will return
.IR c .
.I Ungetc
returns
.IR c .
.PP
One character of pushback is always guaranteed, but as long as there is
sufficient memory, an effectively infinite amount of pushback is allowed.
Attempts to push
.B EOF
are rejected.
.PP
A successful call to
.I fseek
erases all memory of pushed back characters.
.SH "SEE ALSO"
getc(3), fseek(3), setvbuf(3)
.SH "RETURN VALUE"
.I Ungetc
returns
.SM
.B EOF
if it cannot push back the given character for any reason
(this includes attempts to push
.BR EOF ).