wchar -> char

Не решал этот вопрос серьезно, однако, /usr/include/wchar.h:
----
This file is part of the GNU C Library.
....
/*
* ISO C99 Standard: 7.24
* Extended multibyte and wide character utilities <wchar.h>
*/
....
/* The X/Open standard demands that most of the functions defined in
the <wctype.h> header must also appear here. This is probably
because some X/Open members wrote their implementation before the
ISO C standard was published and introduced the better solution.
We have to provide these definitions for compliance reasons but we
do this nonsense only if really necessary. */
#if defined __USE_UNIX98 && !defined __USE_GNU
# define __need_iswxxx
# include <wctype.h>
----

>The X/Open standard demands that most of the functions defined in
the <wctype.h> header must also appear here ..............
не понял, что именно вы имеете в виду ?

Что есть стандарты определения указанных типов, которые перечислены выше.