pointcircletest.cs

this is a good book for the visual c#

// Fig. 10.3: PointCircleTest.cs
// Demonstrating inheritance and polymorphism.

using System;
using System.Windows.Forms;

namespace PointCircle
{
   // PointCircleTest class definition
   class PointCircleTest
   {
      // main entry point for application.
      static void Main( string[] args )
      {
         Point point1 = new Point( 30, 50 );
         Circle circle1 = new Circle( 120, 89, 2.7 );

         string output = "Point point1: " + point1.ToString() +
            "\nCircle circle1: " + circle1.ToString();

         // use 'is a' relationship to assign 
         // Circle circle1 to Point reference
         Point point2 = circle1;

         output += "\n\nCircle circle1 (via point2): " + 
            point2.ToString();

         // downcast (cast base-class reference to derived-class
         // data type) point2 to Circle circle2
         Circle circle2 = ( Circle ) point2;

         output += "\n\nCircle circle1 (via circle2): " + 
            circle2.ToString();

         output += "\nArea of circle1 (via circle2): " + 
            circle2.Area().ToString( "F" );

         // attempt to assign point1 object to Circle reference
         if ( point1 is Circle )
         {
            circle2 = ( Circle ) point1;
            output += "\n\ncast successful";
         }
         else
         {
            output += "\n\npoint1 does not refer to a Circle";
         }

         MessageBox.Show( output, 
            "Demonstrating the 'is a' relationship" );

      } // end method Main

   } // end class PointCircleTest
}

/*
 **************************************************************************
 * (C) Copyright 2002 by Deitel & Associates, Inc. and Prentice Hall.     *
 * All Rights Reserved.                                                   *
 *                                                                        *
 * DISCLAIMER: The authors and publisher of this book have used their     *
 * best efforts in preparing the book. These efforts include the          *
 * development, research, and testing of the theories and programs        *
 * to determine their effectiveness. The authors and publisher make       *
 * no warranty of any kind, expressed or implied, with regard to these    *
 * programs or to the documentation contained in these books. The authors *
 * and publisher shall not be liable in any event for incidental or       *
 * consequential damages in connection with, or arising out of, the       *
 * furnishing, performance, or use of these programs.                     *
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*/