C#多重继承

using System;

namespace InheritanceApplication {

   class Shape {

      public void setWidth(int w) {
         width = w;
      }

      public void setHeight(int h) {
         height = h;
      }
      protected int width;
      protected int height;
   }

   // Base class PaintCost
   public interface PaintCost {
      int getCost(int area);
   }

   // Derived class
   class Rectangle : Shape, PaintCost {

      public int getArea() {
         return (width * height);
      }

      public int getCost(int area) {
         return area * 70;
      }
   }

   class RectangleTester {

      static void Main(string[] args) {
         Rectangle Rect = new Rectangle();
         int area;
         Rect.setWidth(5);
         Rect.setHeight(7);
         area = Rect.getArea();

         // Print the area of the object.
         Console.WriteLine("Total area: {0}",  Rect.getArea());
         Console.WriteLine("Total paint cost: ${0}" , Rect.getCost(area));
         Console.ReadKey();
      }
   }
}