FWIDE(3)                   POSIX Programmer's Manual                  FWIDE(3)



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

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.1-2017
       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.1-2017, <stdio.h>, <wchar.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  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.opengroup.org/unix/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 .



IEEE/The Open Group                  2017                             FWIDE(3)
