/* File : example.h */ class Shape { public: Shape() { nshapes++; } virtual ~Shape() { nshapes--; } double x, y; void move(double dx, double dy); virtual double area() = 0; virtual double perimeter() = 0; static int nshapes; enum SomeEnum { First = 0, Second, Third, Last = 1000 }; }; class Circle : public Shape { private: double radius; public: Circle(double r) : radius(r) { } virtual double area(); virtual double perimeter(); }; class Square : public Shape { private: double width; public: Square(double w) : width(w) { } virtual double area(); virtual double perimeter(); };