NAME
ungetc —
un-get character from input
stream
LIBRARY
library “libc”
SYNOPSIS
#include
<stdio.h>
int
ungetc(int
c, FILE
*stream);
DESCRIPTION
Theungetc()
function pushes the character c (converted to an
unsigned char) back onto the input stream pointed to by
stream. The pushed-backed 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
(fseek(3),
fsetpos(3), or
rewind(3)) will discard the pushed back characters.
One character of push-back is guaranteed, but as long as there is sufficient memory, an effectively infinite amount of pushback is allowed.
If a character is successfully pushed-back, the end-of-file indicator for the stream is cleared.
RETURN VALUES
The ungetc() function returns the
character pushed-back after the conversion, or EOF
if the operation fails. If the value of the argument c
character equals EOF, the operation will fail and
the stream will remain unchanged.
SEE ALSO
STANDARDS
The ungetc() function conforms to
ANSI X3.159-1989 (“ANSI C89”)
and IEEE Std 1003.1-2001
(“POSIX.1”).
HISTORY
An ungetc() function appeared in
Version 7 AT&T UNIX.