friend ostream& operator<< (ostream& os, somedata &a);
ostream& operator<< (ostream& os, somedata &a) { return os << a.member1 << "," << a.member2 << endl; }
friend bool operator== (const somdata &left, const somedata &right); bool operator == (const somdata &left, const somedata &right) { return left.member1 == right.member1 ... }