NAME
ungetc() — push character back into input stream
SYNOPSIS
#include <stdio.h>
int ungetc(int c, FILE *stream);
Obsolescent Interface
int ungetc_unlocked(int c, FILE *stream);
DESCRIPTION
ungetc()
inserts the character
c
(converted to an unsigned char)
into the buffer associated with an input
stream.
That character,
c,
is returned by the next call to
getc()
(see
getc(3S))
on that
stream.
A successful intervening call to a file positioning function with
stream
(fseek(),
fsetpos(),
or
rewind())
erases all memory of the inserted characters.
ungetc()
affects only the buffer associated with the input
stream.
It does not affect the contents of the file corresponding to
stream.
One character of pushback is guaranteed.
If
c
equals EOF,
ungetc()
does nothing to the buffer and returns EOF.
Obsolescent Interface
ungetc_unlocked()
pushes character back into input stream.
APPLICATION USAGE
After
ungetc()
is applied to a stream, the stream becomes byte-oriented (see
orientation(5)).
RETURN VALUE
If successful,
ungetc()
and
ungetc_unlocked()
return
c
and clear the end-of-file indicator for the stream.
ungetc()
and
ungetc_unlocked()
return EOF
if they cannot insert the character.
WARNINGS
ungetc_unlocked()
is an obsolescent interface supported only for compatibility with
existing DCE applications. New multithreaded applications should use
ungetc().
STANDARDS CONFORMANCE
ungetc(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C
Printable version
