Create your own exception class based on Exception : Custom Exception « Language Basics « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Language Basics
3. Custom Exception

using System;
using System.Collections;

public class MyException : Exception
{
    public MyException( String reason, Exception inner ) :base( reason, inner ) {
    }
}

public class MainClass
{
    static void Main() {
        try {
            try {
                ArrayList list = new ArrayList();
                list.Add( 1 );

                Console.WriteLine( "Item 10 = {0}", list[10] );
            }
            catch( ArgumentOutOfRangeException x ) {
                throw new MyException( "I'd rather throw this",x ) ;
            }
            finally {
                Console.WriteLine( "Cleaning up..." );
            }
        }
        catch( Exception x ) {
            Console.WriteLine( x );
            Console.WriteLine( "Done" );
        }
    }
}

Cleaning up...
MyException: I'd rather throw this ---> System.ArgumentOutOfRangeException: Index was out of range.
Must be non-negative and less than the size of the collection.
Parameter name: index
   at System.Collections.ArrayList.get_Item(Int32 index)
   at MainClass.Main()
   --- End of inner exception stack trace ---
   at MainClass.Main()
Done