C#学习.使用多态求矩形的面积和周长，求圆形的面积和周长

1.先写一个形状的抽象类，和获取面积，周长的抽象方法

    public abstract class Shape
    {
        public abstract double GetArea();
        public abstract double GetPerimter();
    }

2.写个圆形的类，继承形状类，弄个私有属性半径r，重写获取面积周长的方法

  public 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 GetPerimter()
        {
            return Math.PI * 2 * this.R;
        }
    }

3.写个矩形的类，继承形状类，私有属性长和宽，重写获取面积周长的方法

  public 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 height,double width)
        {
            this.Height = height;
            this.Width = width;
        }

        public override double GetArea()
        {
            return this.Width * this.Height;
        }

        public override double GetPerimter()
        {
            return 2 * this.Width * this.Height;
        }
    }

4.实现调用

    class Program
    {
        static void Main(string[] args)
        {
            //使用多态求矩形的面积和周长，求圆形的面积和周长
            Shape shape = new Circle(5);
            double Area = shape.GetArea();
            double Perimter = shape.GetPerimter();
            Console.WriteLine(\”周长是{0}，面积是{1}\”, Perimter, Area);

            Shape shape2 = new Square(5,4);
            Area = shape2.GetPerimter();
            Perimter = shape2.GetArea();
            Console.WriteLine(\”周长是{0}，面积是{1}\”, Perimter, Area);
            Console.ReadLine();
        }
    }