头歌C++ 第8章 虚函数与多态性

第8章 虚函数与多态性

一、实训目的
1.掌握运算符重载的方法；
2.学习使用虚函数实现动态多态性；

二、实训内容
1.公有继承 —— 学生信息类
掌握运算符重载的方法；
2.摩托车类
学习使用虚函数实现动态多态性。

三、实训所实现系统主要功能
1.坐标计算
重载运算符Point p，p++，++p，p–，–p
2.摩托车类
输出把基类中 Run、Stop 声明为虚函数，进行测试
四、实训系统核心代码及必要说明
1.坐标计算

#include 
using namespace std;

class Point
{
	int _x, _y;
public:
	Point(int x=0, int y=0) : _x(x), _y(y) {}
	Point& operator++();
	Point operator++(int);
	Point& operator--();
	Point operator--(int);
	friend ostream& operator << (ostream& o, const Point& p);
};

/********** Begin **********/
Point& Point :: operator++()
{
	_x++;	_y++;
	return *this;
}

Point Point :: operator++(int)
{
	Point t = *this;
	++(*this);
	return t;
}

Point& Point :: operator--()
{
	_x--;	_y--;
}

Point Point :: operator--(int)
{
	Point t = *this;
	--(*this);
	return t;
}


/**********  End  **********/

ostream& operator << (ostream& o, const Point& p) {
	o << '(' << p._x << ", " << p._y << ')';
	return o;
}

int main()
{
	int x,y;
	cin>>x>>y;
	Point p(x, y);
	cout << p << endl;
	cout << p++ << endl;
	cout << ++p << endl;
	cout << p-- << endl;
	cout << --p << endl;
	return 0;
}

2.摩托车类

#include 
using namespace std;


/********** Begin **********/
class Vehicle 
{
	public:
		virtual void Run(){
			cout << "vehicle run!" << "\n";
		}
		virtual void Stop(){
			cout << "vehicle stop!" << "\n";
		}
};
class Bicycle : virtual public Vehicle 
{
	public:
		void Run(){
			cout << "bicycle run!" << "\n";
		}
		void Stop(){
			cout << "bicycle stop!" << "\n";
		}
};

class Motorcar : virtual public Vehicle 
{
	public:
		void Run(){
			cout << "motocar run!" << "\n";
		}
		void Stop(){
			cout << "motocar stop!" << "\n";
		}
};
/**********  End  **********/

class Motorcycle : public Bicycle, public Motorcar
{
public:
	void Run() {cout << "motocycle run!" << endl;}
	void Stop() {cout << "motocycle stop!" << endl;}
};

int main()
{
	Vehicle v;
	v.Run();
	v.Stop();
	Bicycle b;
	b.Run();
	b.Stop();
	Motorcar m;
	m.Run();
	m.Stop();
	Motorcycle mc;
	mc.Run();
	mc.Stop();
	Vehicle* vp = &v;
	vp->Run();
	vp->Stop();
	vp = &b;
	vp->Run();
	vp->Stop();
	vp = &m;
	vp->Run();
	vp->Stop();
	vp = &mc;
	vp->Run();
	vp->Stop();
	return 0;
}