towupper - convert a wide character to uppercase
The towupper function is the wide-character
equivalent of the toupper function. If wc is a
wide character, it is converted to uppercase. Characters
which do not have case are returned unchanged. If wc
is WEOF, WEOF is returned.
The towupper function returns the uppercase
equivalent of wc, or WEOF if wc is
ISO/ANSI C, UNIX98
The behaviour of towupper depends on the LC_CTYPE
category of the current locale.
This function is not very appropriate for dealing with
Unicode characters, because Unicode knows about three cases:
upper, lower and title case.