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fwide (3)
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 value > 0 if stream is wide-character
oriented, that is, if wide-character I/O is permitted but char I/O is
disallowed. It returns a value < 0 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 opera-
tion 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 non-zero, the fwide() function first attempts to set
stream's orientation (to wide-character oriented if mode > 0, or to
byte oriented if mode < 0). It then returns a value denoting the cur-
rent orientation, as above.
RETURN VALUE
The fwide() function returns the stream's orientation, after possibly
changing it. A return value > 0 means wide-character oriented. A
return value < 0 means byte oriented. A return value of zero means
undecided.
CONFORMING TO
C99, POSIX.1-2001.
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)
GNU 2007-07-26 FWIDE(3)
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