基类成员访问方式

1.通过派生类的对象直接访问。前提是public继承

2.通过基类成员函数直接访问基类成员。无论哪种继承方式。基类的public和private都不可以以这种方式访问

3.通过基类名称访问被派生类重定义所隐藏的成员

#include<bits/stdc++.h>
using namespace std;

class Rectangle
{
    public:
        void setLength(double h) {
            length = h;
        }
        void setWidth(double w)
        {
            width = w;
        }
        double getLength()
        {
            return length;
        }
        double getWidth()
        {
            return width;
        }
        double area()
        {
            return width*length;
        }
        double volume()
        {
            return 0;
        }
        void print()
        {
            cout << "
Length = " << length << "
Width = " << width;
        }
    protected:
        double length;
        double width;
};

class Cube:public Rectangle
{
    public:
        void setHigh(double h)
        {
            high = h;
        }
        double getHigh()
        {
            return high;
        }
        double area()
        {
            //重定义area函数 
            return 2*(width*length + width*high + high*length);
        }
        double volume()
        {
            return width*length*high;
        }
        
        void print()
        {
            Rectangle::print();
            cout << "
high = " << high << endl;
        }
    private:
        double high;
};

int main()
{
    Cube c1;
    c1.setLength(4);
    c1.setHigh(3);
    c1.setWidth(5);
    
    c1.Rectangle::print();
    c1.print();
    cout << "Cube area = " << c1.area() << endl;
    cout << "Cube bottom area = " << c1.Rectangle::area() << endl;
    cout << "Cube volume = " << c1.volume() << endl;
    return 0;
}