Open Source Software

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 ||
       _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

   This  page  is  part of release 4.09 of the Linux man-pages project.  A
   description of the project, information about reporting bugs,  and  the
   latest     version     of     this    page,    can    be    found    at
   https://www.kernel.org/doc/man-pages/.



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