C++ Primer Plus学习笔记之继承类的初始化顺序
基类的构造函数,析构函数和操作符函数operator=是不能被派生类继承的;
那么,当创建一个派生类对象时,怎样调用基类的构造函数对基类的数据进行初始化呢???
答案是:构造函数执行时遵行先兄长(基类),再客人(对象成员),后自己(派生类)的顺序;
另一方面,执行析构函数时,先执行派生类的析构函数,再执行基类的析构函数。原因是,对基类的破坏隐含了对派生类的破坏,所以派生类的析构函数必须先执行;
#include<iostream> using namespace std; class Member { public: Member() { cout<<"Member created"<<endl; } ~Member() { cout<<"Member destroyed"<<endl; } }; class Base { public: Base() { cout<<"Base created"<<endl; } ~Base() { cout<<"Base destroyed"<<endl; } }; class Derived:public Base { public: Derived() { cout<<"Derived created"<<endl; } ~Derived() { cout<<"Derived destroyed"<<endl; } private: Member m; }; int main(int argc,char *argv[]) { Derived d; return 0; }运行结果:
Base created
Member created
Derived created
Derived destroyed
Member destroyed
Base destroyed