fwide(3) - Linux manual page (original) (raw)

fwide(3) Library Functions Manual fwide(3)

NAME top

   fwide - set and determine the orientation of a FILE stream

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#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 top

   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 top

   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 top

   C11, POSIX.1-2008.

HISTORY top

   POSIX.1-2001, C99.

NOTES top

   Wide-character output to a byte oriented stream can be performed
   through the [fprintf(3)](../man3/fprintf.3.html) function with the **%lc** and **%ls** directives.

   Char oriented output to a wide-character oriented stream can be
   performed through the [fwprintf(3)](../man3/fwprintf.3.html) function with the **%c** and **%s**
   directives.

SEE ALSO top

   [fprintf(3)](../man3/fprintf.3.html), [fwprintf(3)](../man3/fwprintf.3.html)

COLOPHON top

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Linux man-pages 6.10 2024-07-23 fwide(3)

Pages that refer to this page:wprintf(3)