fwide - set and determine the orientation of a FILE stream
#include <wchar.h>
int fwide(FILE *stream, int mode);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
fwide():
_XOPEN_SOURCE >= 500 || _ISOC99_SOURCE
||
_POSIX_C_SOURCE >= 200112L
When
mode is zero, the
fwide() function determines the current
orientation of
stream. It returns a positive value if
stream is
wide-character oriented, that is, if wide-character I/O is permitted but char
I/O is disallowed. It returns a negative value if
stream is byte
oriented—that is, if char I/O is permitted but wide-character I/O is
disallowed. It returns zero if
stream has no orientation yet; in this
case the next I/O operation might change the orientation (to byte oriented if
it is a char I/O operation, or to wide-character oriented if it is a
wide-character I/O operation).
Once a stream has an orientation, it cannot be changed and persists until the
stream is closed.
When
mode is nonzero, the
fwide() function first attempts to set
stream's orientation (to wide-character oriented if
mode is
greater than 0, or to byte oriented if
mode is less than 0). It then
returns a value denoting the current orientation, as above.
The
fwide() function returns the stream's orientation, after possibly
changing it. A positive return value means wide-character oriented. A negative
return value means byte oriented. A return value of zero means undecided.
POSIX.1-2001, POSIX.1-2008, C99.
Wide-character output to a byte oriented stream can be performed through the
fprintf(3) function with the
%lc and
%ls directives.
Char oriented output to a wide-character oriented stream can be performed
through the
fwprintf(3) function with the
%c and
%s
directives.
fprintf(3),
fwprintf(3)