#include <stdio.h> int
ungetc (int c FILE *stream);
DESCRIPTION
The
ungetc ();
function pushes the character
Fa c
(converted to an unsigned char)
back onto the input stream pointed to by
Fa stream .
The pushed-back 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
(fseek3,
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.
The file-position indicator is decremented
by each successful call to
ungetc (;);
if its value was 0 before a call, its value is unspecified after
the call.
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
Fa c
character equals
EOF
the operation will fail and the stream will remain unchanged.
