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  1. // dynamic allocation and polymorphism
  2. #include <iostream>
  3. using namespace std;
  4.  
  5. class Polygon {
  6.   protected:
  7.     int width, height;
  8.   public:
  9.     Polygon (int a, int b) : width(a), height(b) {}
  10.     virtual int area (void) =0;
  11.     void printarea()
  12.       { cout << this->area() << '\n'; }
  13. };
  14.  
  15. class Rectangle: public Polygon {
  16.   public:
  17.     Rectangle(int a,int b) : Polygon(a,b) {}
  18.     int area()
  19.       { return width*height; }
  20. };
  21.  
  22. class Triangle: public Polygon {
  23.   public:
  24.     Triangle(int a,int b) : Polygon(a,b) {}
  25.     int area()
  26.       { return width*height/2; }
  27. };
  28.  
  29. int main () {
  30.   Polygon * ppoly1 = new Rectangle (4,5);
  31.   Polygon * ppoly2 = new Triangle (4,5);
  32.   ppoly1->printarea();
  33.   ppoly2->printarea();
  34.   delete ppoly1;
  35.   delete ppoly2;
  36.   return 0;
  37. }
Success #stdin #stdout 0s 4284KB
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https://ideone.com/dck6eb
language:
C++ (gcc 8.3)
created:
6 years ago
visibility:
public

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