// Fig. 9.9: circle2.h // Definition of class Circle #ifndef CIRCLE2_H #define CIRCLE2_H #include "point2.h" class Circle : public Point { friend ostream &operator<<( ostream &, const Circle & ); public: // default constructor Circle( double r = 0.0, int x = 0, int y = 0 ); void setRadius( double ); // set radius double getRadius() const; // return radius double area() const; // calculate area protected: // accessible to derived classes double radius; // radius of the Circle }; #endif