The <wctype.h> include file declares functions used to classify wide characters:
| iswalnum | iswctype | iswprint | iswxdigit |
| iswalpha | iswdigit | iswpunct | towlower |
| iswblank | iswgraph | iswspace | towupper |
| iswcntrl | islower | iswupper | wctype |
<wctype.h> also defines the types wint_t and wctype_t, and the macro WEOF, which expands to a constant expression of type wint_t whose value does not correspond to any member of the extended character set and indicates EOF.