What you need to know about re-throwing exceptions

ExceptionDemo.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;

namespace ExceptionTest
{
    class DataLayer
    {
        public static int DoSomething()
        {
            int a = 10;
            int b = 0;
            int c = a / b;
            return c;
        }
    }
    
    class BusinessLayer
    {
        public static int DoSomething()
        {
            return DataLayer.DoSomething();
        }
    }

    class ServiceLayer
    {
        /// <summary>
        /// Creates a new exception by throwing ex in the catch block.
        /// </summary>
        public static int DoSomething1()
        {
            try
            {
                return BusinessLayer.DoSomething();
            }
            catch (Exception ex)
            {
                Log.LogException(ex, "Something crashed...", EventLogEntryType.Error);
                throw ex;
            }
        }

        /// <summary>
        /// Re-throws the exception by calling throw; in the catch block. 
        /// </summary>
        public static int DoSomething2()
        {
            try
            {
                return BusinessLayer.DoSomething();
            }
            catch (Exception ex)
            {
                Log.LogException(ex, "Something crashed...", EventLogEntryType.Error);
                throw;
            }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine();
            try
            {
                ServiceLayer.DoSomething1();
            }
            catch (Exception ex)
            {
                Console.ForegroundColor = ConsoleColor.Yellow;
                Console.WriteLine("[New exception thrown]");
                Console.WriteLine(RemoveLongPath(ex.ToString()));
                Console.WriteLine();
            }

            try
            {
                ServiceLayer.DoSomething2();
            }
            catch (Exception ex)
            {
                Console.ForegroundColor = ConsoleColor.Red;
                Console.WriteLine("[Exception from data layer re-thrown]");
                Console.WriteLine(RemoveLongPath(ex.ToString()));
                Console.WriteLine();
            }
        }

        static string RemoveLongPath(string text)
        {
            return text.Replace(@"C:\Users\jonasf\Documents\Visual Studio 2005\Projects\ExceptionTest\ExceptionTest\Program.cs", @"C:\Program.cs");
        }
    }
}