HP-UX Reference (11i v1 00/12) - 3 Library Functions N-Z (vol 7)

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STANDARD Printed by: Nora Chuang [nchuang] STANDARD

/build/1111/BRICK/man3/nan.3m

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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 suc-

cessful intervening call to a ﬁle positioning function with stream (fseek(), fsetpos(),orrewind())

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

ungetc() is a thread-safe interface. It is not async-cancel-safe. A cancellation point may occur when a

thread is executing ungetc().

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().