Difference between Throw and Throw ex in C#

Difference between Throw and Throw ex in C# | Throw vs Throw ex in C#

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Difference between Throw and Throw ex in C#

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As you all know throw and throw ex are used in catch part of the thy..catch block. Let’s try to understand one by one first and then try to understand what is the exact difference between them.

Understanding of throw:

using System;

namespace Throw_vsThrow_ex_csharp
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                Method1();
            }
            catch (Exception ex)
            {
                Console.WriteLine(Convert.ToString(ex.StackTrace));
            }
            Console.ReadLine();
        }

        private static void Method2()
        {
            try
            {
                throw new Exception("only use throw in catch block");
            }
            catch (Exception ex)
            {
                throw;
            }
        }

        private static void Method1()
        {
            try
            {
                Method2();
            }
            catch (Exception ex)
            {
                throw;
            }
        }
    }
}

Here we have two methods named with Method1() and Method2(). From Method1() method2() has been called and here Method2 is throwing custom exception “only use throw in catch block”. As we have used Throw only in Method1 and Method2, it will print full trace of exception as shown below image.

Throw-In-C#
Throw-In-C#

Understanding of throw ex:

using System;

namespace Throw_vsThrow_ex_csharp
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                Method1();
            }
            catch (Exception ex)
            {
                Console.WriteLine(Convert.ToString(ex.StackTrace));
            }

            Console.ReadLine();
        }

        private static void Method2()
        {
            try
            {
                throw new Exception("only use throw ex in catch block");
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        private static void Method1()
        {
            try
            {
                Method2();
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }


    }
}

Here we have two methods named with Method1() and Method2(). From Method1() method2() has been called and here Method2 is throwing custom exception “only use throw in catch block”. As we have used Throw only in Method1 and Method2, it will not print full trace of exception as we have got in throw as shown below image. We could get only last exception details. So StackTrace has been overridden by Method2().

Throw-ex-in-C#
Throw-ex-in-C#

Conclusion with difference:

throw : If we use “throw” statement, it preserve original error stack information. In exception handling “throw” with empty parameter is also called re-throwing the last exception.

throw ex : If we use “throw ex” statement, stack trace of exception will be replaced with a stack trace starting at the re-throw point. It is used to intentionally hide stack trace information.

Folks you should also refer below articles for better understanding of differences between confusing concepts:

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