Compares the characters in a wide-character string against a set
    of wide characters. The function returns the length of the first
    substring comprised entirely of characters in the set of wide
    characters.

    Format

      #include  <wchar.h>

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

  Additional Information (explode) :

• Arguments
• Description
• Return Value
• Example