父类析构函数必须设置成虚函数

将可能会被继承的父类的析构函数设置为虚函数，可以保证当我们new一个子类，然后使用基类指针指向该子类对象，释放基类指针时可以释放掉子类的空间，防止内存泄漏

class Parent { public: virtual ~Parent() { cout << "delete Parent" << endl; } }; class Child : public Parent { public: virtual ~Child() { cout << "delete Child" << endl; } }; int main(int argc, char* argv[]) { Parent* p1 = new Child(); delete p1; return 0; }

输出

delete Child delete Parent