If you want users to be able to programmatically distinguish between some error conditions, you can create your own user-defined exceptions. The .NET Framework provides a hierarchy of exception classes ultimately derived from the base class Exception. Each of these classes defines a specific exception, so in many cases you only have to catch the exception. You can also create your own exception classes by deriving from the Exception class.

Example: -

 using System; 
 namespace MindstickCustomeExceptionDemo
 {
 public class MindstickEmployeeListNotFoundException : Exception
 {
 public MindstickEmployeeListNotFoundException()
 { 
 }
 public MindstickEmployeeListNotFoundException(string message):base(message)
 { 
 } 
 }
 class CustomException
 {
 static void Main(string[] args)
 {
 try
 {
 throw new MindstickEmployeeListNotFoundException("\n\n::Mindstick Employee List not found::\n\n"); 
 }
 catch (MindstickEmployeeListNotFoundException ce)
 {
 Console.WriteLine(ce.ToString());
 }
 Console.ReadKey();
 }
 }
 }

Code Description: -

1.       Using System (include the System namespace).

2.  Create a namespace with MindstickCustomeExceptionDemo named.

4.  Create a public class with MindstickEmployeeListNotFoundException

named and inherit the Exception class.

6.  Create a class constructor of MindstickEmployeeListNotFoundException

without parameter.

9.  Create a class constructor of MindstickEmployeeListNotFoundException

with parameter.

13.Create a class with CustomException named.

15.   Create Main method.

17.Start try block.

19.   Thrown the exception with its exception class name.

21.   This catch block.

23.   Print the exception message.

Output: -

If I pass any message in the form of string while thrown the exception then on console screen show passed string message.

In line number 19. I have pass throw newMindstickEmployeeListNotFoundException("\n\n::Mindstick Employee List not found::\n\n");then it message will show console screen.

ScreenShot:

In line number 19. I don't pass any message in string format such as: - throw newMindstickEmployeeListNotFoundException();then it will show system message in console screen.

Screenshot: -