ungetc.3s (2010 09)

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ungetc(3S) ungetc(3S)
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().
SEE ALSO
flockfile(3S), fseek(3S), fgetpos(3S), getc(3S), setbuf(3S), orientation(5), thread_safety(5).
STANDARDS CONFORMANCE
ungetc(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1