Returns the number of wide characters in a wide-character
    string. The returned length does not include the terminating
    null character.

    Format

      #include  <wchar.h>

      size_t wcslen  (const wchar_t *wstr);

1 - Argument

 wstr

    A pointer to a null-terminated wide-character string.

2 - Return Value

    x                  The length of the wide-character string,
                       excluding the terminating null wide character.