AbstractClass

//Abstract Class Example

   #include <iostream> 
   using namespace std; 
   // Base class 
   class Shape 
   { 
     public: 
       // pure virtual function providing interface framework. 
       virtual int getArea() = 0; 
       void setWidth(int w) 
       { 
         width = w; 
       } 
       void setHeight(int h) 
       { 
         height = h; 
       } 
     protected: 
       int width; 
       int height; 
   }; 
   // Derived classes 
   class Rectangle: public Shape 
   { 
     public: 
       int getArea() 
       { 
         return (width * height); 
       } 
   }; 
   class Triangle: public Shape 
   { 
     public: 
       int getArea() 
       { 
         return (width * height)/2; 
       } 
   }; 
   int main(void) 
   { 
     Rectangle Rect; 
     Triangle Tri; 
     Rect.setWidth(5); 
     Rect.setHeight(7); 
     // Print the area of the object. 
     cout << "Total Rectangle area: " << Rect.getArea() << endl; 
     Tri.setWidth(5); 
     Tri.setHeight(7); 
     // Print the area of the object. 
     cout << "Total Triangle area: " << Tri.getArea() << endl; 
     return 0; 
   }