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fwide - set and determine the orientation of a FILE stream
#include <wchar.h>
int fwide (FILE* stream, int mode);
When mode is zero, the fwide
function determines the current orientation of stream. It returns a value
> 0 if stream is wide-character oriented, i.e. if wide character I/O is permitted
but char I/O is disallowed. It returns a value < 0 if stream is byte oriented,
i.e. 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 non-zero, the fwide function first attempts
to set stream's orientation (to wide-character oriented if mode > 0, or to
byte oriented if mode < 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 return value > 0 means wide-character
oriented. A return value < 0 means byte oriented. A return value zero means
undecided.
ISO/ANSI C, UNIX98
fprintf(3)
, fwprintf(3)
Wide-character output to a byte oriented stream can be performed through
the fprintf function with the %lc and %ls directives.
Char oriented output
to a wide-character oriented stream can be performed through the fwprintf
function with the %c and %s directives.
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