基类指针赋值兼容规则

*/
#include <iostream>
#include <vector>
using namespace std;
class Base{
private:
 int x;
 int y;
public:
 Base(int x,int y)
 {
 this->x=x;
 this->y=y;
 }
};
class Derived:public Base{
private:
 int z;
public:
 Derived(int z):Base(z-1,z+1)
 {
 this->z=z;
 }
};
int main(void)
{
 //Derived *p=new Base(2,1);//因为派生类指针映射范围大
   Base *p=new Derived(1);
   delete p;
 return 0;
}