int fwide(FILE *stream, int mode);
The fwide() function shall determine the orientation of the stream pointed to by stream. If mode is greater than zero, the function first attempts to make the stream wide-oriented. If mode is less than zero, the function first attempts to make the stream byte-oriented. Otherwise, mode is zero and the function does not alter the orientation of the stream.
If the orientation of the stream has already been determined, fwide() shall not change it.
Since no return value is reserved to indicate an error, an application wishing to check for error situations should set errno to 0, then call fwide(), then check errno, and if it is non-zero, assume an error has occurred.
The fwide() function shall return a value greater than zero if, after the call, the stream has wide-orientation, a value less than zero if the stream has byte-orientation, or zero if the stream has no orientation.
The fwide() function may fail if:
The stream argument is not a valid stream.
The following sections are informative.
A call to fwide() with mode set to zero can be used to determine the current orientation of a stream.
COPYRIGHTPortions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .