使用多态求矩形的面积和周长以及圆形的面积和周长

//使用多态求矩形的面积和周长以及圆形的面积我周长

Shape shape = new Circle(5); //new Square(5,6);
double area = shape.GetArea();
double perimeter = shape.GetPerimeter();
Console.WriteLine(" 这个形状的面积是{0}，周长是{1}",area,perimeter);
Console.ReadKey();

}

public abstract class Shape
{

public abstract double GetArea();
public abstract double GetPerimeter();

}




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

public class Square : Shape
{
private double _height;
public double Height
{
get { return _height; }
set { _height = value; }

}
private double _width;
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.Height * this.Width;
}
public override double GetPerimeter()
{
return (this.Height+this.Width)*2;
}
}