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 ||
           _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.

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008, 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)

COLOPHON

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GNU                                                2016-03-15                                           FWIDE(3)