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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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fwide(3) Library Functions Manual fwide(3)
fwide - set and determine the orientation of a FILE stream
Standard C library (libc, -lc)
#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
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.
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.
C11, POSIX.1-2008.
POSIX.1-2001, C99.
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.
fprintf(3), fwprintf(3)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
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part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 fwide(3)
Pages that refer to this page: wprintf(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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