towlower − convert a wide character to lowercase
wint_t towlower (wint_t wc);
The towlower function is the wide-character equivalent of the tolower function. If wc is a wide character, it is converted to lowercase. Characters which do not have case are returned unchanged. If wc is WEOF, WEOF is returned.
The towlower function returns the lowercase equivalent of wc, or WEOF if wc is WEOF.
ISO/ANSI C, UNIX98
The behaviour of towlower 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.