FWIDE(3) Linux Programmer s Manual FWIDE(3)

NAME fwide - set and determine the orientation of a FILE stream

SYNOPSIS #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; or cc -std=c99

DESCRIPTION When mode is zero, the fwide() function determines the current orienta- tion of stream. It returns a positive value if stream is wide-charac- ter 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, i.e., 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-char- acter I/O operation).

Once a stream has an orientation, it cannot be changed and persists until the stream is closed.

When mode is non-zero, 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.

RETURN VALUE The fwide() function returns the streams 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.


NOTES 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 per- formed through the fwprintf(3) function with the %c and %s directives.

SEE ALSO fprintf(3), fwprintf(3)

COLOPHON This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.

GNU 2007-07-26 FWIDE(3)