继承以及保护的案例

/* 继承以及保护的案例 */

#include<iostream>

using namespace std;

const double PI = 3.141592657;

// 点
class point
{
public:
    
    point(int a,int b):x(a),y(b)
    {
    
    }

    void setxy(int a,int b)
    {
        x = a;
        y = b;
    }
    
    int getx() const
    {
        return x;
    }

    int gety() const
    {
        return y;
    }

protected:// 保护成员 外部不可访问 内部可以 继承的可以
    int x;
    int y;
};


class circle : public point
{
public:
    circle(double length,int a,int b):point(a,b),length(length)
    {

    }

    double getlength() const
    {
        return length;
    }
    
    void setlength(double db)
    {
        length = db;
    }

protected:
    double length;// 半径
};

class cylinder : public circle
{
public:
    cylinder(double high,double length,int a,int b):circle(length,a,b),high(high)
    {
    
    }
    
    double gethigh() const
    {
        return high;
    }
    
    void sethigh(double db)
    {
        high = db;
    }
    
    double tiji()
    {
        return (this->length)*(this->length)*PI*high;
    }

    double mianji()
    {
        return (this->length)*(this->length)*PI*2 + (this->length)*PI*2 *high;
    }
protected:
    double high;
};

void main()
{
    
    cylinder cy1(100,100,450,560);
    cin.get();
}