虚析构函数

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什么是虚析构函数？

虚析构函数确保继承类对象在析构的时候从继承类析构。
经常用于子类对象被赋值给父类对象指针的情景。

例1：下面例子说明没有虚析构函数是对象析构顺序。

#include <iostream> using namespace std; class Base {     public:        Base() {            cout << "Base class constructor ..." << endl;        }        ~Base() {            cout << "Base class destructor ..." << endl;        }}; class Derived : public Base {     public:        Derived() {            cout << "Derived class constructor ..." << endl;        }        ~Derived() {            cout << "Derived class destructor ..." << endl;        }}; void main(){    Base* base;    base = new Derived();    delete base;} OUTPUT:Base class constructor ...Derived class constructor ...Base class destructor ...

例2：下面例子说明有虚析构函数时对象析构顺序。

#include <iostream> using namespace std; class Base {     public:        Base() {            cout << "Base class constructor ..." << endl;        }        virtual ~Base() {            cout << "Base class destructor ..." << endl;        }}; class Derived : public Base {     public:        Derived() {            cout << "Derived class constructor ..." << endl;        }        ~Derived() {            cout << "Derived class destructor ..." << endl;        }}; void main(){    Base* base;    base = new Derived();    delete base;} OUTPUT:Base class constructor ...Derived class constructor ...Derived class destructor ...Base class destructor ...

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