c++知识点总结--静态与动态类型

Posted 2020-09-10

对象的静态类型（static type），就是它在程序中被声明时所采用的类型

对象的动态类型（dynamic type）是指“目前所指对象的类型”

 

vitual 函数是动态绑定而来，调用一个virtual函数时，究竟调用哪一个函数实现，取决于发出调用的那个对象的动态类型

class Shape{
    public:
        enum ShapeColor{ Red, Green, Blue = 1, Org };
        void printColor(){
            cout << Red << Green << Blue << Org << endl;
        }
        virtual void draw(ShapeColor color = Red)const = 0;
    };
    class Rectangle :public Shape{
    public:
        virtual void draw(ShapeColor color = Green) const{
            cout << "this is rectangle,color is " << color << endl;
        }
    };
    class Circle :public Shape{
    public:
        virtual void draw(ShapeColor color)const{
            cout << "this is circle,color is " << color << endl;
        }
    };
    static void test(){
        Shape *ps;
        Shape *pc = new Circle;
        Shape *pr = new Rectangle;

        pc->draw();
        pr->draw();
    }
默认参数是静态绑定，pr输出值仍然是Shape的默认值