int iswalpha_l(wint_t c,
               locale_t loc);

iswalpha_l returns true if the wide character c is alphabetic in the locale loc. Any character for which iswupper_l or iswlower_l returns true is considered alphabetic in addition to any of the locale-specific set of alphabetic characters for which none of iswcntrl_l, iswdigit_l, iswpunct_l, or iswspace_l is true.