C++之虚析构函数

先给个例子：

class Animal{public:    Animal();    ~Animal();    virtual void voice() = 0;};Animal::Animal(){    cout << "Animal()" << endl;}Animal::~Animal(){    cout << "~Animal()" << endl;}class Dog:public Animal{public:    Dog();    ~Dog();    virtual void voice();};Dog::Dog(){    cout << "Dog()" << endl;}Dog::~Dog(){    cout << "~Dog()" << endl;}void Dog::voice(){    cout << "I am a dog: wang wang wang wang" << endl;}class Cat:public Animal{public:    Cat();    ~Cat();    virtual void voice();};Cat::Cat(){    cout << "Cat()" << endl;}Cat::~Cat(){    cout << "~Cat()" << endl;}void Cat::voice(){    cout << "I am a cat: miao miao miao" << endl;}int main(){    Animal *ani = new Dog;    ani->voice();    delete ani;    ani = new Cat;    ani->voice();    delete ani;    system("pause");    return 0;}

输出结果为：

这里是在堆上创建的对象，delete了ani，发现结果中只有Dog和Cat的构造，却没有Dog和Cat的析构，而只析构了Animal，这就会发生内存泄漏。

解决的办法就是对基类Animal的析构函数变成虚函数，就会先调用子类的析构函数，然后再调用基类的析构函数，这样就形成了完全析构，避免了内存泄漏的问题，这里只需要在Animal的析构函数前面加个virtual即可：

class Animal{public:    Animal();    virtual ~Animal();     //虚析构函数    virtual void voice() = 0;};

输出结果：