un-get character from input stream
() function pushes the character
(converted to an
) back onto the input stream pointed to by
. The pushed-backed 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
) 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.
() function returns the character
pushed-back after the conversion, or
the operation fails. If the value of the argument
, the operation will fail and the stream
will remain unchanged.
() function conforms to
() function first appeared in
Version 7 AT&T UNIX