size_t rfind(const char* sz, size_t nStart = npos,
size_t n = npos) const;
/// as find, but from the end
size_t rfind(char ch, size_t nStart = npos) const;
size_t rfind(const char* sz, size_t nStart = npos,
size_t n = npos) const;
/// as find, but from the end
size_t rfind(char ch, size_t nStart = npos) const;