Part7 继承与派生 7.3基类与派生类类型转换

//7-3类型转换规则举例
#include<iostream>
using namespace std;
class Base1{
public:
    void display() const {
        cout << "Base1::display()" << endl;
    }
};
class Base2: public Base1{
public:
    void display() const {
        cout << "Base2::display()" << endl;
    }
};
class Derived: public Base2{
public:
    void display() const{
        cout << "Derived::dispaly()" << endl;
    }
};

void fun(Base1 *ptr){//参数为指向基类对象的指针,通过基类对象名、指针只能使用从基类继承的成员
    ptr->display();        //对象指针->成员名
}

int main(){
    Base1 base1;
    Base2 base2;
    Derived derived;
    
    fun(&base1);
    fun(&base2);
    fun(&derived);
    return 0;
}