C# 0 The Complete Reference

catch

 in 

Main( )

. Understand, however, 

that if 

GenException( )

 had caught the exception, then it never would have been passed 

back to 

Main( )

.

The Consequences of an Uncaught Exception

Catching one of the standard exceptions, as the preceding program does, has a side benefit: 

It prevents abnormal program termination. When an exception is thrown, it must be caught 

by some piece of code, somewhere. In general, if your program does not catch an exception, 

it will be caught by the runtime system. The trouble is that the runtime system will report 

an error and terminate the program. For instance, in this example, the index out-of-bounds 

exception is not caught by the program:

// Let the C# runtime system handle the error.

using System;

class NotHandled {

  static void Main() {

    int[] nums = new int[4];

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    Console.WriteLine("Before exception is generated.");

    // Generate an index out-of-bounds exception.

    for(int i=0; i < 10; i++) {

      nums[i] = i;

      Console.WriteLine("nums[{0}]: {1}", i, nums[i]);

    }

  }

}

When the array index error occurs, execution is halted and the following error message 

is displayed:

Unhandled Exception: System.IndexOutOfRangeException:

          Index was outside the bounds of the array.

   at NotHandled.Main()

Although such a message is useful while debugging, you would not want others to see it, to 

say the least! This is why it is important for your program to handle exceptions itself.

As mentioned earlier, the type of the exception must match the type specified in a 

catch

.

If it doesn’t, the exception won’t be caught. For example, the following program tries to 

catch an array boundary error with a