fwide

FWIDE(3)                    Linux Programmer's Manual                   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 5.13 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/.



GNU                                2021-03-22                           FWIDE(3)