第十、十一周项目1 - 点-圆-圆柱类族的设计（3）

#include<iostream>
#include<cmath>
using namespace std;
#define PI 3.1415926
class Point
{
public:
    void setPoint(float i,float j);
    float getX(){return x;}
    float getY(){return y;}
    float dr(Point &p1,Point &p2);
private:
    float x;
    float y;
};
void Point::setPoint(float i,float j)
{
    x=i;
    y=j;
}
float Point::dr(Point &p1,Point &p2)
{
    float dr=0,dx=0,dy=0;
    dx=p1.x-p2.x;
    dy=p1.y-p2.y;
    dr=sqrt(dx*dx+dy*dy);
    return dr;
}
class Circle:public Point
{
public:
    Circle(float x1,float y1,float x2,float y2){midpoint.setPoint(x1,y1);aroundpoint.setPoint(x2,y2);}
    float setR();
    void circle_area();
    float getR(){return r;}
    float getarea(){return area;}
    float lcircle();
private:
    float area;
    float r;
    Point midpoint;
    Point aroundpoint;
};
float Circle::setR()
{
    r=dr(midpoint,aroundpoint);
    return r;
}
void Circle::circle_area()
{
    r=setR();
    area=PI*r*r;
    cout<<"底面圆的面积为："<<area<<endl;
}
float Circle::lcircle()
{
    r=setR();
    float l;
    l=2*PI*r;
    return l;
}  

class Cylinder:public Circle
{
public:
    Cylinder(float x1,float y1,float x2,float y2,float h1):Circle(x1,y1,x2,y2),h(h1){}
    void cylinderarea();
    void cylinder_volume();
private:
    float h;
};
void Cylinder::cylinderarea()
{
    float s;
    s=2*getarea()+lcircle()*h;
    cout<<"圆柱体的表面积为："<<s<<endl;
}
void Cylinder::cylinder_volume()
{
    float v;
    v=getarea()*h;
    cout<<"圆柱体的体积为："<<v<<endl;
}
int main()
{  

    Cylinder cy1(0,0,3,4,1.0);
    cy1.circle_area();
    cy1.cylinderarea();
    cy1.cylinder_volume();
    return 0;
}

运行结果