2

01.#include<iostream>
02.using namespace std;
03.class Circle
04.{
05.public:
06.    Circle(double p)
07.    {
08.        radius=p;
09.    }
10.    double area()
11.    {
12.        return (3.14*radius*radius);
13.    }
14.private:
15.    double radius;
16.};
17.int main()
18.{
19.    Circle cir1(5.0);
20.    double Area=cir1.area();
21.    cout<<"圆的面积为："<<Area;
22.    cout<<endl;
23.    return 0;
24.}