2019-07-20--继承之构建对象规则

一、构建孙子对象时，调用顺序如下：

• 1.基类
• 2.父类
• 3.成员
• 4.自身
• 基类有成员变量时那么孙子儿子自己都得初始化
• 成员有成员变量时，自己也得给其初始化

#include "String.h"
#include 
using namespace std;

class Base{
protected:
String m_name;
public:
    Base(const String& name):m_name(name) {
        cout <<"Base construcr:" << this << endl;
    }
    ~Base(){
        cout <<"Base distrucr:" << this << endl;
    }
    

};
class Derive:public Base{
public:
    Derive(const String& name):Base(name){
        cout <<"Derive construcr:" << this << endl;
    }
    ~Derive(){
        cout <<"Derive distrucr:" << this << endl;
    }
    

};

class Member{
//String m_name;
public:
    Member(/*const String& name*/)/*:m_name(name)*/{
        cout <<"Member construcr:" << this << endl;
    }
    ~Member(){
        cout <<"Member distrucr:" << this << endl;
    }
    

};

class SubDerive : public Derive{
public:
    SubDerive(const String& name):Derive(name)/*,m(name)*/{
        cout <<"SubDerive construcr:" << this << endl;
    }
    ~SubDerive(){
        cout <<"SubDerive distrucr:" << this << endl;
    }
    void Print()const{
        cout << m_name << endl;
    }
private:
    Member m;
};
int main(){
    SubDerive d("zhangsan");
    d.Print();
}

二、结果

[kiosk@foundation89 C++]$ vim String.h
[kiosk@foundation89 C++]$ vim String.cpp
[kiosk@foundation89 C++]$ g++ construct_test.cpp String.cpp 
[kiosk@foundation89 C++]$ ./a.out
Base construcr:0x7fff6e4b65f0
Derive construcr:0x7fff6e4b65f0
Member construcr:0x7fff6e4b65f8
SubDerive construcr:0x7fff6e4b65f0
zhangsan
SubDerive distrucr:0x7fff6e4b65f0
Member distrucr:0x7fff6e4b65f8
Derive distrucr:0x7fff6e4b65f0
Base distrucr:0x7fff6e4b65f0
[kiosk@foundation89 C++]$