多态参考代码.doc

1224: 多态-虚函数问题 Description int main() { double x,y,r; cinxyr; //圆心的点坐标及圆的半径 Point *p; p=new Point(x,y); p-Display(); p=new Circle(x,y,r); p-Display(); return 0; } 说明：圆周率PI的取值为3.14 提示：Display应设计为虚函数 Input Output Sample Input 0 0 1 Sample Output Point(0,0) Circles center:Point(0,0) Radius:1 Area:3.14 Perimeter:6.28 **************************************************************** #include iostream using namespace std; const double PI=3.14; class Point { private: double x,y; public: Point(double x1,double y1); virtual void Display(); //虚函数 }; Point::Point(double x1,double y1) { x=x1;y=y1;} void Point::Display() { coutPoint(x,y)endl;} class Circle:public Point { private: double r; public: Circle(double x1,double y1,double r1); void Display(); double Area(); double Perimeter(); }; double Circle::Area() { return PI*r*r;} double Circle::Perimeter() { return 2*PI*r;} Circle::Circle(double x1,double y1,double r1):Point(x1,y1) { r=r1; } void Circle::Display() { coutCircles center:; Point::Display(); //excute Point::Display of base class coutRadius:rendl; coutArea:Area()endl; coutPerimeter:Perimeter()endl; } int main() { double x,y,r; cinxyr; //圆心的点坐标及圆的半径 Point *p; p=new Point(x,y); p-Display(); p=new Circle(x,y,r); p-Display(); return 0; } 1229: 多态-抽象类1 Description class Shape { public: Shape(); virtual double Area()=0; virtual double Perimeter() = 0; }; class Circle:public Shape { public: Circle(double rr); double Radius(); double Area(); double Perimeter(); private: double r; //圆的半径 }; class In_Square:public Circle { public: In_Square(double rr); double Area(); double Perimeter(); }; class Ex_Square:public Circle { public: Ex_Square(double x); double Area(); double Perimeter(); }; int main() { Shape *ptr; double r; cinr;