FAQ 19.14 How are objects of a class printed?

Objects of a class are normally printed via a friend function called operator<<. Here is an example of such a friend function.

 #include <iostream> using namespace std; class Fred { public:   friend ostream& operator<< (ostream& ostr, const Fred& x) throw(); protected:   int i_; }; ostream& operator<< (ostream& ostr, const Fred& x) throw() {   ostr << x.i_;   return ostr; } 

The function operator<< is a friend rather than a member, so the Fred parameter appears on the right side of the <<.