size_t rfind(const String& sub) const {

        if (size < sub.size) return size;

		auto searchsize = size - sub.size;

		auto pend = str + searchsize;

		auto p = pend;

		auto psubend = sub.str + sub.size;

		while(p >= str)
		{

			auto pitem = p;

			auto psubitem = sub.str;

			while(pitem < psubend)
			{

				if(*pitem != *psubitem)
				{

					goto next;

				}
				pitem++;
				psubitem++;

			}

			return p - str;
next:

			p--;

		}

        return size;
    }