The
ungetwc ();
function pushes the wide character
Fa wc
(converted to an
Vt wchar_t )
back onto the input stream pointed to by
Fa stream .
The pushed-backed wide 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
fseek(3),
fsetpos(3),
or
rewind(3)
will discard the pushed back wide characters.
One wide 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.
RETURN VALUES
The
ungetwc ();
function
returns
the wide character pushed-back after the conversion, or
WEOF
if the operation fails.
If the value of the argument
Fa c
character equals
WEOF
the operation will fail and the stream will remain unchanged.
