FWIDE(3)

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

SYNOPSIS
     #include <wchar.h>
     int fwide(FILE *FP, int MODE)
     int _fwide_r(struct _reent *PTR, FILE *FP, int MODE)

DESCRIPTION
When MODE is zero, the `fwide' function determines the current orientation of FP. It returns a value > 0 if FP is wide-character oriented, i.e. if wide character I/O is permitted but char I/O is disallowed. It returns a value < 0 if FP is byte oriented, i.e. if char I/O is permitted but wide character I/O is disallowed. It returns zero if FP 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, unless the stream is re-opened with freopen, which removes the orientation of the stream.
   When MODE is non-zero, the `fwide' function first attempts to set FP's orientation (to wide-character oriented if MODE > 0, or to byte oriented if MODE < 0). It then returns a value denoting the current orientation, as above.

RETURNS
The `fwide' function returns FP'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.

PORTABILITY
C99, POSIX.1-2001.

SEE ALSO
fwide is part of the library. The full documentation for is maintained as a Texinfo manual. If info and are properly installed at your site, the command

    info

will give you access to the complete manual.