C#使用多态求方形面积周长和圆的面积周长

  class class1{public static void Main(string[] args){//使用多态求矩形面积与周长和圆的面积与周长Shape cl = new Circle(5);double clarea = cl.GetArea();double clpar = cl.GetPerimeter();Console.WriteLine("这个圆的面积是{0},周长是{1}", Math.Round(clarea, 2), Math.Round(clpar, 2));Shape sq = new Square(5, 10);double sqarea = sq.GetArea();double sqpar = sq.GetPerimeter();Console.WriteLine("这个方形的面积是{0},周长是{1}", Math.Round(sqarea, 2), Math.Round(sqpar, 2));Console.ReadKey();}}//声明一个抽像类public abstract class Shape{public abstract double GetArea();public abstract double GetPerimeter();}class Circle:Shape{private double _r;public double R{get {return _r;}set {_r = value;}}public Circle(double r){this.R = r;}public override double GetArea(){return Math.PI * this.R * this.R;}public override double GetPerimeter(){return 2 * Math.PI * this.R;}}class Square : Shape{private double _height;private double _width;public double Height{get{return _height;}set{_height = value;}}public double Width{get {return _width;}set {_width = value;}}public Square(double w, double h){this.Height = h;this.Width = w;}public override double GetArea(){return this.Width * this.Height;}public override double GetPerimeter(){return (this.Width + this.Height) * 2;}}