#include <iostream> #include <cmath> using namespace std; class Point { public: Point(double x=0,double y=0); void setPoint(double,double); double getx() { return x; } double gety() { return y; } void display(); protected: double x,y; }; class Circle:public Point { public: Circle(double x=0,double y=0,double R=0); void setR(double,double,double);//半径 double getR() { return R; } double areas();//圆面积 protected: double R; }; Point::Point(double a,double b) { x=a; y=b; } void Point::setPoint(double a,double b) { x=a; y=b; } void Point::display() { cout<<"( "<<getx()<<","<<gety()<<")"<<endl; } Circle::Circle(double a,double b,double r):Point(a,b),R(r) {} void Circle::setR(double a,double b,double r) { x=a; y=b; R=r; } double Circle::areas() { return 3.14*R*R; } int main() { Point p1(3,3),p2(8,8); Circle c(2,2,4); cout<<"第一点"; p1.display(); cout<<"第二点"; p2.display(); cout<<"原点为:"<<"( "<<c.getx()<<","<<c.gety()<<")"<<" 半径为:"<<c.getR()<<" 的圆的面积为:"<<c.areas()<<endl; return 0; }
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原文:http://blog.csdn.net/caicongyang/article/details/25243619