ungetwc - push back a wide character onto a FILE stream
#include <wchar.h>
wint_t ungetwc(wint_t wc, FILE *stream);
The
ungetwc() function is the wide-character equivalent of the
ungetc(3) function. It pushes back a wide character onto
stream
and returns it.
If
wc is
WEOF, it returns
WEOF. If
wc is an invalid
wide character, it sets
errno to
EILSEQ and returns
WEOF.
If
wc is a valid wide character, it is pushed back onto the stream and
thus becomes available for future wide-character read operations. The
file-position indicator is decremented by one or more. The end-of-file
indicator is cleared. The backing storage of the file is not affected.
Note:
wc need not be the last wide-character read from the stream; it can
be any other valid wide character.
If the implementation supports multiple push-back operations in a row, the
pushed-back wide characters will be read in reverse order; however, only one
level of push-back is guaranteed.
The
ungetwc() function returns
wc when successful, or
WEOF
upon failure.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
ungetwc () |
Thread safety |
MT-Safe |
POSIX.1-2001, POSIX.1-2008, C99.
The behavior of
ungetwc() depends on the
LC_CTYPE category of the
current locale.
fgetwc(3)