12.纯虚函数

纯虚函数在基类中声明，在调用父类的纯虚函数，会在子类中是实现

 

#include <iostream>
using namespace std;

class Shape
{
public:
int x, y;
public:
void set(int x, int y)
{
this->x = x;
this->y = y;
}
virtual void S()=0;
};

class Cirle :public Shape
{
public:
void S()
{
cout << "x+y" << x + y << endl;
}
};

class Pirle :public Shape
{
public:
void S()
{
cout << "x-y" << x - y << endl;
}
};

class Dirle :public Shape
{
public:
void S()
{
cout << "x*y" << x * y << endl;
}
};

int main()
{
//声明父类的指针
Shape* p;
Cirle c; c.set(1,2);

Pirle x; x.set(8,6);

Dirle d; d.set(8,5);

p = &c; p->S();
p = &x; p->S();
p = &d; p->S();
system("pause");
return 0;

}