Class Base

base_code/derived_base.cpp:24–31

};

class Base {
public:
    Base():value(20) {}
    virtual ~Base() = default;
    static void test1() { cout << "Base test1..." << endl; }
private:  //私有
    int value;
};

/**
 * 子类对父类成员的访问权限跟如何继承没有任何关系，