wint_t towupper(wint_t c);

towupper converts a lowercase letter to a corresponding uppercase letter.

If the argument c is a wide character for which iswlower is true and there are one or more corresponding wide characters, in the current current locale, for which iswupper is true, towupper returns one (and always the same one for any given locale) of the corresponding wide characters; otherwise, c is returned unchanged.