C++mid102_2

#include <iostream>
using namespace std;

int num =1;

class A{
public:
    //static int num;
    A():id(num){
        name = id;
        num++;
        cout<<"Constructor: Obj "<<id<<" of type A. Name is"<<name<<endl;
    }
    //A(const A &a):id(1){cout<<"hiiii"<<endl;}
    ~A(){cout<<"Destructor: Obj "<<id<<" of type A. Name is"<<name<<endl;
    }
    const int id;
    int name;
};

//int A::num=1;

class B : public A{
public:
    B():id(num){
        name = id;
        num++;
        cout<<"Constructor: Obj"<<id<<" of type B. Name is"<<name<<endl;
    }
    ~B(){cout<<"Destructor: Obj"<<id<<" of type B. Name is"<<name<<endl;
    }
    const int id;
    int name;
};
//一開始(id,name): o1(1,1) o2(3,3)
void swap1(A o1, B o2){
    A tmp = o1;
    cout<<&o1<<endl;
    cout<<&tmp<<endl;
    cout<<tmp.id<<endl;

    o1.name = o2.name;
    o2.name = tmp.name;
}
//解構順序: tmp(1,1)->o1(1,3)->o2(3,1)(B->A)

void swap2(A &o1, B &o2){
    A tmp = o1;
    o1.name = o2.name;
    o2.name = tmp.name;
}

int main(){
    A o1;
    B o2;
    cout<<o1.id<<" "<<o1.name<<endl;
    cout<<o2.id<<" "<<o2.name<<endl;
    swap1(o1, o2);
    cout<<o1.id<<" "<<o1.name<<endl;
    cout<<o2.id<<" "<<o2.name<<endl;

    {
        static A o3;
        swap2(o3,o2);
        cout<<o1.id<<" "<<o1.name<<endl;
        cout<<o2.id<<" "<<o2.name<<endl;
        cout<<o3.id<<" "<<o3.name<<endl;
    }



    //程式結束時解構順序:依照變數建立的順序，由後往前倒回去解
    //先解子類別再解父類別
    //static最後解
}