Man page - fwide(3)

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Manual

fwide

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
RETURN VALUE
STANDARDS
HISTORY
NOTES
SEE ALSO

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)