PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       fwide — set stream orientation

SYNOPSIS

       #include <stdio.h>
       #include <wchar.h>

       int fwide(FILE *stream, int mode);

DESCRIPTION

       The functionality described on this reference page is aligned with the ISO C standard. Any
       conflict between the requirements described here and the ISO C standard is  unintentional.
       This volume of POSIX.1‐2008 defers to the ISO C standard.

       The  fwide()  function shall determine the orientation of the stream pointed to by stream.
       If mode is greater than zero, the  function  first  attempts  to  make  the  stream  wide-
       oriented.  If mode is less than zero, the function first attempts to make the stream byte-
       oriented. Otherwise, mode is zero and the function does not alter the orientation  of  the
       stream.

       If the orientation of the stream has already been determined, fwide() shall not change it.

       The fwide() function shall not change the setting of errno if successful.

       Since  no  return  value is reserved to indicate an error, an application wishing to check
       for error situations should set errno to 0, then call fwide(), then check errno, and if it
       is non-zero, assume an error has occurred.

RETURN VALUE

       The fwide() function shall return a value greater than zero if, after the call, the stream
       has wide-orientation, a value less than zero if the stream has byte-orientation,  or  zero
       if the stream has no orientation.

ERRORS

       The fwide() function may fail if:

       EBADF  The stream argument is not a valid stream.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       A  call  to fwide() with mode set to zero can be used to determine the current orientation
       of a stream.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       The Base Definitions volume of POSIX.1‐2008, <stdio.h>, <wchar.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2013  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013  by  the
       Institute  of  Electrical  and  Electronics  Engineers,  Inc and The Open Group.  (This is
       POSIX.1-2008 with the  2013  Technical  Corrigendum  1  applied.)  In  the  event  of  any
       discrepancy  between  this  version and the original IEEE and The Open Group Standard, the
       original IEEE and The Open Group Standard is the referee document. The  original  Standard
       can be obtained online at http://www.unix.org/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .