旱冰场造价

今天开始跟着贺利坚老师的博客，进行c++的学习，积累代码量；

#include <iostream>using namespace std;const double Pi=3.1415926;const int M=20; //水泥场地每平米造价  const int N=35; //围栏每米造价class Circle{public:void setRadius(double r);//设置半径 double area();           //求圆的面积double circumfernce();   //求圆的周长private:double radius;};void Circle::setRadius(double r){radius=r;}double Circle::area(){double s;s=Pi*radius*radius;return s;   //代码直接return Pi*radius*radius;更简洁，我怎么没想到呢}double Circle::circumfernce(){double s;s=2*Pi*radius;return s;   //同上}int main(){double r;cout<<"旱冰场的半径：";cin>>r;Circle c;c.setRadius(r);cout<<"旱冰场的造价为 "<<M*c.area()+N*c.circumfernce()<<"元。"<<endl;return 0;}