多态练习

<pre name="code" class="cpp">#include <iostream>
using namespace std;
class Vehicle  //交通工具
{
public:
    void run() const
    {
        cout << "run a vehicle. "<<endl; 
    }
};
class Car: public Vehicle  //汽车
{
public:
    void run() const
    {
        cout << "run a car. "<<endl;
    }
};
class Airplane: public Vehicle  //飞机
{
public:
    void run() const
    {
        cout << "run a airplane. "<<endl;
    }
};
int main()
{
    cout<<"(a) 直接用对象访问成员函数: "<<endl;
    Vehicle v;
    v.run();
    Car car;
    Airplane airplane;
    car.run();
    airplane.run();
    cout<<"(b)用指向基类的指针访问成员函数: "<<endl;
    Vehicle *vp;
    vp=&car;
    vp->run();
    vp=&airplane;
    vp->run();
    return 0;
}