学步园

#include <iostream>
#define PI 3.14
using namespace std;
class Circle
{
private:
	double radius;
public:
	void setRadius(double r);
	double area();
	double circumference();
};

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：