C in a Nutshell

Name

fwide

Synopsis

Determines whether a stream is byte-character- or wide-character-oriented

#include <stdio.h>
#include <wchar.h>
intfwide( FILE *fp, int mode );

The fwide() function either gets or sets the character type orientation of a file, depending on the value of the mode argument:

mode > 0

The fwide() function attempts to change the file to wide-character orientation.

mode < 0

The function attempts to change the file to byte-character orientation.

mode = 0

The function does not alter the orientation of the stream.

In all three cases, the return value of fwide() indicates the stream’s orientation after the function call in the same way:

Greater than 0

After the fwide() function call, the file has wide-character orientation.

Less than 0

The file now has byte-character orientation.

Equal to 0

The file has no orientation.

The normal usage of fwide() is to call it once immediately after opening a file to set it to wide-character orientation. Once you have determined the file’s orientation, fwide() does not change it on subsequent calls. If you do not call fwide() for a given file, its orientation is determined by whether the first read or write operation is byte-oriented or wide-oriented. You can remove a file’s byte or wide-character orientation by calling freopen(). For more information, see "Byte-Oriented and Wide-Oriented Streams" in Chapter 13.

Example

See the example for fputws() in this chapter.

See Also

The many functions for working with streams of wide characters, listed in Table 16-2 ...