Class pointer and virtual function : Virtual « Function « C++

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Class pointer and virtual function
Class pointer and virtual function

#include <iostream>
using namespace std;

class figure {
protected:
  double x, y;
public:
  void set_dim(double i, double j=0) {
    x = i;
    y = j;
  }
  virtual void show_area() {
    cout << "No area computation defined ";
    cout << "for this class.\n";
  }
;

class triangle : public figure {
  public:
    void show_area() {
      cout << "Triangle with height ";
      cout << x << " and base " << y;
      cout << " has an area of ";
      cout << x * 0.5 * y << ".\n";
    }
};

class rectangle : public figure {
  public:
    void show_area() {
      cout << "Rectangle with dimensions ";
      cout << x << "x" << y;
      cout << " has an area of ";
      cout << x *  y << ".\n";
    }
};

class circle : public figure {
  public:
    void show_area() {
      cout << "Circle with radius ";
      cout << x;
      cout << " has an area of ";
      cout << 3.14 * x * x << ".\n";
    }
;
  
int main()
{
  figure *p;  // create a pointer to base type

  triangle t; // create objects of derived types
  rectangle s;
  circle c;

  p = &t;
  p->set_dim(10.05.0);
  p->show_area();

  p = &s;
  p->set_dim(10.05.0);
  p->show_area();  

  p = &c;
  p->set_dim(9.0);
  p->show_area()

  return 0;
}


           
       
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4.Use virtual function to define interface.Use virtual function to define interface.
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6.Virtual function and public inheritanceVirtual function and public inheritance
7.Virtual function and three level inheritanceVirtual function and three level inheritance
8.Virtual function for two derived classesVirtual function for two derived classes
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