Indicates if a wide character is classed as a digit in the
    program's current locale.

    Format

      #include  <wctype.h> (ISO C)

      #include  <wchar.h> (XPG4)

      int iswdigit  (wint_t wc);

1 - Argument

 wc

    An object of type wint_t. The value of wc must be representable
    as a wchar_t in the current locale, or must equal the value
    of the macro WEOF. If it has any other value, the behavior is
    undefined.

2 - Return Values

    nonzero            If a decimal digit.
    0                  If not a decimal digit.