Implement in C++. Please make the friend std::ostream& operator<<(std::ostream& os, const Date& d); to a virtual operator overload.

class Date {

public:

virtual std::string getFormat() = 0;

friend std::ostream& operator<<(std::ostream& os, const Date& d);

};

ostream& operator<<(ostream& os, Date& d) { os << d.getFormat(); return os; }