const float PI = 3.14; 
class Circle {
private:
    float radius;

public:
    // 构造函数
    Circle(float r) {
        radius = r;
    }

    // 计算圆的面积
    float getArea() {
        return PI * radius * radius;
    }

    // 计算圆的周长
    float getGirth() {
        return 2 * PI * radius;
    }
};
#include<iostream>
using namespace std;
int main()
{
	float r;
	cout << "请输入圆的半径：";
	cin >> r;                                     //从键盘接受半径的值
    Circle c1(r);                            //将值赋值给半径并调用定义好的函数
    cout<<"圆的面积为："<<c1.getArea()<<endl;
    Circle c2(r);
    cout<<"圆的周长为："<<c2.getGirth()<<endl;
}