用面向对象的方法求圆的面积

/* 用面向对象的方法求圆的面积 */ #include <iostream> #define pi 3.1415926 using namespace std; class Round { private: double r;//半径 public: void setR(double R) { r = R; } double getArea() { double area; area = pi*r*r; return area; } }; int main() { Round r1; cout << "请输入圆的半径："<<endl; double radii; cin >> radii; r1.setR(radii); cout << "半径为" << radii << "的圆的面积为：" << r1.getArea() << endl; system("pause"); }