2018-01-12//1.2继承

//1.2继承

#include<bits/stdc++.h>

using namespace std;

class base{//基类或超类

public:

    base(){ }

    void f(char *s="unknown"){

                     cout<<"function f() in base call from "<<s<<endl;

                    h();

                }

protected:

    void g(char *s="unknown"){

        cout<<"function g() in base call from "<<s<<endl;

        }

private:

    void  h(){

        cout<<"function h() in base"<<endl;

    }

};

class DL_1:public/*说明派生类和基类中的public和protected一致，若为protected，则派生类中，基类的public和protected都变为protected*/

virtual base {//子类或派生类，可以使用基类中protected或public的数据成员和成员函数，不需重复定义，不能使用基类的private！

public:

    void f(char *s="unknown"){

        cout<<"function f() in DL_1 call from "<<s<<endl;

        g("DL_1");

        h("DL_1");

    }

    void h(char *s="unknown"){

        cout<<"function h() in DL_1 call from "<<s<<endl;

        }

};

/*DL_1是从base中派生出来的类，可以调用base中公有和受保护的成员函数，

而由DL_1派生出来的派生类DL_2可以调用DL_1可以调用的成员函数*/

class DL_2:public virtual base {

public :

    void f(char *s="unknown"){

        cout<<"function f() in DL_2 call from "<<s<<endl;

        g("DL_2");

//    h();//error:base::h() is not accessible,不能访问基类私有成员

    }

};

class DL_3 :public DL_1, public DL_2{//如果DL_2和DL_3不加关键词virtual，则会产生二义性

public :

    void f(char *s="unknown"){

        cout<<"function f() in DL_3 call from "<<s<<endl;

        g("DL_3");

        base::f("DL_3");//前置作用域

        DL_1::h("DL_3");

        }

};

int main(){

    base bc;

    DL_1 dl_1;

    DL_2 dl_2;

    DL_3 dl_3;

    bc.f("main(0)");

    dl_1.f("main(1)");

    dl_1.h("main(1)");

    dl_2.f("main(2)");

    dl_3.f("main(3)");

}