//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;

}

}