13-11.cpp

为初学者提供的最佳的C++程序设计源程序库

#include<iostream.h>
class car
{
public:
  double distance;
  car(double f)
  {
    distance=f;
  }
  virtual void travel_time()
  {
    cout<<"car:Travel time at 120 kph:";
    cout<<distance/120<<'\n';
  }
};
class truck:public car
{
public:
  truck(double f):car(f)
   {}
   void travel_time()
   {
    cout<<"truck:Travel time at 80 kph:";
    cout<<distance/80<<'\n';
  }
};
main()
{
  car *p,car_time(150.0);
  truck truck_time(150);
  p=&car_time;
  p->travel_time();
  p=&truck_time;
  p->travel_time();
  return 0;
}