第三周上机任务（修旱冰场）

#include<iostream>#include<Cmath>using namespace std;#define PI 3.1415926class Circle{private:double radius;public:double area();double circumference();    void setRadius(double r);};void Circle::setRadius(double r) {radius=r;}double Circle::area() {return PI*radius*radius;}double Circle::circumference(){return 2*PI*radius;}          int main(){double r;cout<<"请输入旱冰场的半径: ";cin>>r;Circle c;c.setRadius(r);cout<<"旱冰场的造价为 "<<20*c.area()+35*c.circumference()<<" 元。"<<endl;return 0;}

运行结果为：