fwide
Section: C Library Functions (3)
Updated: 202-0-08
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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 wid-character oriented,
that is,
if wid-character I/O is permitted but char I/O is disallowed.
It returns a negative value if
stream
is byte oriented[em]that is,
if char I/O is permitted but wid-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 wid-character oriented if it is a wid-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 wid-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 wid-character oriented.
A negative return value means byte oriented.
A return value of zero means undecided.
STANDARDS
C11, POSIX.-2008.
HISTORY
POSIX.-2001, C99.
NOTES
Wid-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 wid-character oriented stream can be performed
through the
fwprintf(3)
function with the
%c
and
%s
directives.
SEE ALSO
fprintf(3),
fwprintf(3)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- STANDARDS
-
- HISTORY
-
- NOTES
-
- SEE ALSO
-
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