构造： 现有父类后有子类

析构：和构造顺序相反，先析构子类后析构父类

#include <iostream>

class A
{
public:
    A()
    {
        std::cout << "ctor father" << std::endl;
    }
    virtual ~A()
    {
        std::cout << "dtor fathor" << std::endl;
    }
};

class a : public A
{
public:
    a()
    {
        std::cout << "ctor son" << std::endl;
    }
    ~a()
    {
        std::cout << "dtor son" << std::endl;
    }
};

int main(void)
{
    a aa;
    return 0;
}

无情的摸鱼机器