fwide(3) — Linux manual page

fwide(3)                Library Functions Manual                fwide(3)

NAME

       fwide - set and determine the orientation of a FILE stream

LIBRARY

       Standard C library (libc, -lc)

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.

STANDARDS

       C11, POSIX.1-2008.

HISTORY

       POSIX.1-2001, 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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Linux man-pages 6.9.1          2024-05-02                       fwide(3)

Pages that refer to this page: wprintf(3)

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