多态的实现手段

1.基类含有虚函数；

2.使用new创建基类对象和子类对象，结果均保留在基类指针变量中；

3.通过基类指针变量调用函数即可事实多态了。

如下列示例代码：

#include <iostream>
using namespace std;

class BaseTest
{
public:
	BaseTest(){}
	BaseTest(const BaseTest&){}
	BaseTest operator= (const BaseTest&){}
	virtual ~BaseTest(){}

	virtual void show(){//虚函数
		cout << "this is BaseTest's show function. " << endl;
	}
};

class DrivedTest: public BaseTest
{
public:
	DrivedTest(){}
	DrivedTest(const DrivedTest&){}
	DrivedTest operator= (const DrivedTest&){}
	~DrivedTest(){}

	void show(){
		cout << "this is DrivedTest's show function." << endl;
	}
};

void main()
{
	BaseTest *bptr = new BaseTest;//基类指针bptr
	bptr->show();//调用基类的show函数
	delete bptr;
	bptr = new DrivedTest;//bptr指向子类
	bptr->show();//调用子类的show函数
}