C++ 虚析构函数简单测试

class Base {
public:
    virtual ~Base() { cout << "~Base" << '\n'; }
};

class Derived : public Base {
public:
    ~Derived() { cout << "~Derived" << '\n'; }
};

int main()
{
    {
        Base* b = new Derived;
        delete b;
    }

    system("pause");
    return EXIT_SUCCESS;
}

析构顺序输出：

~Derived
~Base

如果，把基类的析构函数设置成纯虚函数，也必须要定义，不然编译不过，只定义派生类的函数时不行的。
将析构函数设置成纯虚，目的可能是不能让类实例的作用。

class Base
{
public:
    virtual ~Base() = 0;
};

Base::~Base() { cout << "~Base" << '\n'; } // 必须要定义，不然编译不过。

class Derived : public Base
{
public:
    ~Derived() { cout << "~Derived" << '\n'; }
};

输出：

~Derived
~Base