x                  The converted value.
    0                  Indicates that the string starts with an
                       unrecognized wide character or that the value
                       for base is invalid. If the string starts with
                       an unrecognized wide character, *endptr is set
                       to nptr. The function sets errno to EINVAL.
    ULONG_MAX          Indicates that the converted value would
                       cause an overflow. The function sets errno
                       to ERANGE.