Difference between revisions of "CPP/Classes/PureVirtualFunction"

#include <iostream>
#include <limits>
 
class Point3{
 
public:
  Point(const double xin, const double yin, const double zin) : x(xin), y(yin), z(zin) {}
  Point() x(),y(),z(){};
private:
  double x,y,z;
  virtual void print(){ cout << "(" << x << "," << y << "," << z << ")" << endl; }
};
 
class Coordinate: Point3
{
  void point(){
     cout << "Coordinate (" << x << "," << y << "," << z << ")" << endl; 
  }
};	
 
int main(){
  Point3 p1 = new Point3(1,2,3);
  Coordinate c1 = new Coordinate();
 
  //polymorphism
  Point3 *p = &c1;
  p.print(); //output "Coordinate (0,0,0)"
 
  p = &p1;
  p.print(); //output "(1,2,3)"
 
  return 0;
}

#include <iostream>
 
class Vehicle
{
	public:
        /*
         * Here we declare a Pure Virtual Function
         * This class has now become an abstract class & 
         * it's instances cannot be created. Only pointers.
         *
         */
   	virtual void SeeMeGo()=0;
};
 
/* Some Derived Classes */
class Car : public Vehicle
{
	public:
		void SeeMeGo()
		{
		      	std:cout<<"I'm running at 50mph.\n";
		}
};
 
class Bike : public Vehicle
{
	public:
		void SeeMeGo()
		{
		      	std:cout<<"I'm whooshing at 80mph.\n";
		}
};
 
class Truck : public Vehicle
{
	public:
		void SeeMeGo()
		{
		      	std:cout<<"I'm crawling at 20mph.\n";
		}
};
 
int main(int argc, char *argv[])
{
  //Create a Pointer to Abstract Class Vehicle
  Vehicle *myVehicle;
 
  //Create Some Objects
  Car   myCar;
  Bike  myBike;
  Truck myTruck;
 
  //Call Functions
  myVehicle = &myCar;
  myVehicle->SeeMeGo();
 
  myVehicle = &myBike;
  myVehicle->SeeMeGo();
 
  myVehicle = &myTruck;
  myVehicle->SeeMeGo();
 
  return 1;
}