Compares the characters in a wide-character string against a
    set of wide characters. The function returns the length of the
    initial substring that is comprised entirely of characters that
    are not in the set of wide characters.

    Format

      #include  <wchar.h>

      size_t wcscspn  (const wchar_t *wstr1, const wchar_t *wstr2);

  Additional Information (explode) :

• Arguments
• Description
• Return Value
• Example