// @topic T52015 11/27/2012 -- Inheritance and Polymorphism // @brief Shape interface #ifndef _SHAPE_H_INCLUDED_ #define _SHAPE_H_INCLUDED_ const double PI = 3.1415926; class Shape { public: // polymorphic operations: virtual ~Shape() {} virtual void draw()=0; virtual double area()=0; };//class Shape #endif // _SHAPE_H_INCLUDED_