103 lines
3.4 KiB
Groff
103 lines
3.4 KiB
Groff
.\" Copyright (c) 1990, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to Berkeley by
|
|
.\" Chris Torek and the American National Standards Committee X3,
|
|
.\" on Information Processing Systems.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)ungetc.3 8.1 (Berkeley) 6/4/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd June 4, 1993
|
|
.Dt UNGETC 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm ungetc
|
|
.Nd un-get character from input stream
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In stdio.h
|
|
.Ft int
|
|
.Fn ungetc "int c" "FILE *stream"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn ungetc
|
|
function pushes the character
|
|
.Fa c
|
|
(converted to an unsigned char)
|
|
back onto the input stream pointed to by
|
|
.Fa stream .
|
|
The pushed-back characters will be returned by subsequent reads on the
|
|
stream (in reverse order).
|
|
A successful intervening call,
|
|
using the same stream,
|
|
to one of the file positioning functions
|
|
.Xr ( fseek 3 ,
|
|
.Xr fsetpos 3 ,
|
|
or
|
|
.Xr rewind 3 )
|
|
will discard the pushed back characters.
|
|
.Pp
|
|
One character of push-back is guaranteed,
|
|
but as long as there is sufficient memory,
|
|
an effectively infinite amount of pushback is allowed.
|
|
.Pp
|
|
If a character is successfully pushed-back,
|
|
the end-of-file indicator for the stream is cleared.
|
|
The file-position indicator is decremented
|
|
by each successful call to
|
|
.Fn ungetc ;
|
|
if its value was 0 before a call, its value is unspecified after
|
|
the call.
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn ungetc
|
|
function returns the character pushed-back after the conversion,
|
|
or
|
|
.Dv EOF
|
|
if the operation fails.
|
|
If the value of the argument
|
|
.Fa c
|
|
character equals
|
|
.Dv EOF ,
|
|
the operation will fail and the stream will remain unchanged.
|
|
.Sh SEE ALSO
|
|
.Xr fseek 3 ,
|
|
.Xr getc 3 ,
|
|
.Xr setvbuf 3 ,
|
|
.Xr ungetwc 3
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn ungetc
|
|
function conforms to
|
|
.St -isoC .
|