wctype() is defined for valid character class names as defined in the current locale. The
charclass is a string identifying a generic character class for which codeset-specific type
information is required. The following character class names are defined in all locales:
"alnum", "alpha", "blank", "cntrl", "digit", "graph", "lower", "print",
"punct", "space", "upper" and "xdigit".
Additional character class names defined in the locale definition file (category LC_CTYPE)
can also be specified. The function returns a value of type wctype_t, which can be used as the second argument
to subsequent calls of iswctype(). The wctype() function determines values of wctype_t
according to the rules of the coded character set defined by character type information in
the program ́s locale (category LC_CTYPE). The values returned by wctype() are valid until
a call to setlocale() that modifies the category LC_CTYPE. Restriction
This version of the C runtime system only supports 1-byte characters as wide character
codes. They are of type wchar_t (see stddef.h). (End) | 