ex-11-07

Programming Csharp Source Code(代码) Programming Csharp Source Code

// Example 11-07: Creating a custom exception

namespace Programming_CSharp
{
   using System;

   public class MyCustomException : 
         System.ApplicationException
   {
      public MyCustomException(string message):
         base(message)
      {
            
      }
   }

   public class Test
   {
      public static void Main()
      {
         Test t = new Test();
         t.TestFunc();
      }

      // try to divide two numbers
      // handle possible exceptionsexceptions
      public void TestFunc()
      {
         try
         {
            Console.WriteLine("Open file here");
            double a = 0;
            double b = 5;             
            Console.WriteLine ("{0} / {1} = {2}",
               a, b, DoDivide(a,b));
            Console.WriteLine (
               "This line may or may not print");
         }

            // most derived exception type first
         catch (System.DivideByZeroException e)
         {
            Console.WriteLine(
               "\nDivideByZeroException! Msg: {0}",
               e.Message);
            Console.WriteLine(
               "\nHelpLink: {0}\n", e.HelpLink);
         }
         catch (MyCustomException e)
         {
            Console.WriteLine(
               "\nMyCustomException! Msg: {0}",
               e.Message);
            Console.WriteLine(
               "\nHelpLink: {0}\n", e.HelpLink);
         }
         catch 
         {
            Console.WriteLine(
               "Unknown exception caught");
         } 
         finally
         {
            Console.WriteLine ("Close file here.");
         }

      }

      // do the division if legal
      public double DoDivide(double a, double b)
      {
         if (b == 0)
         {
            DivideByZeroException e = 
               new DivideByZeroException();
            e.HelpLink=
               "http://www.libertyassociates.com";
            throw e;
         }
         if (a == 0)
         {
            MyCustomException e = 
               new MyCustomException(
                  "Can't have zero divisor");
            e.HelpLink =
            "http://www.libertyassociates.com/NoZeroDivisor.htm";
            throw e;
         }
         return a/b;
      }
   }
}