fwide(3)                   Library Functions Manual                   fwide(3)

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

LIBRARY
       Standard C library (libc, -lc)

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
               || _POSIX_C_SOURCE >= 200112L

DESCRIPTION
       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.

RETURN VALUE
       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.

STANDARDS
       C11, POSIX.1-2008.

HISTORY
       POSIX.1-2001, C99.

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
       performed through the fwprintf(3) function with the %c and %s
       directives.

SEE ALSO
       fprintf(3), fwprintf(3)

Linux man-pages 6.7               2023-10-31                          fwide(3)