AT&T UNIX™PC Unix System V Users Manual - tenox

UNGETC ( 3S ) UNGETC ( 3S )
NAME
ungetc - push character back into input stream
SYNOPSIS
#include
int ungetc (c, stream)
char c;
FILE •stream;
DESCRIPTION
Ungetc inserts the character c into the buffer associated with an
input stream . That character, c, will be returned by the next
getc call on that stream. Ungetc returns c, and leaves the file
stream unchanged.
One character of pushback is guaranteed provided something has
been read from the stream and the stream is actually buffered.
If c equals EOF, ungetc does nothing to the buffer and returns
EOF.
Fseek(3S) erases all memory of inserted characters.
SEE ALSO
fseek(3S), getc(3S), setbuf(3S).
DIAGNOSTICS
In order that ungetc perform correctly, a read statement must
have been performed prior to the call of the ungetc function.
Ungetc returns EOF if it can't insert the character. In the case
that stream is stdin , ungetc will allow exactly one character to be
pushed back onto the buffer without a previous read statement.
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