Part 41 - C# Tutorial - Inner Exceptions

The InnerException property returns the Exception instance that caused the current exception.

To look at the inner exception, you have to make this program cuase an exception fail. To do that you have 3 options
1. Enter a Character instead of a number (Causes Format Exception)
2. Or Enter a very big number that an interger cannot hold (Causes Over Flow Exception)
3. Or Enter Zero for Second Number (Causes Divide By Zero Exception)

Part 41 - C# Tutorial - Inner Exceptions

using System;
using System.IO;
class ExceptionHandling
{
    public static void Main()
    {
        try
        {
            try
            {
                Console.WriteLine("Enter First Number");
                int FN = Convert.ToInt32(Console.ReadLine());


                Console.WriteLine("Enter Second Number");
                int SN = Convert.ToInt32(Console.ReadLine());


                int Result = FN / SN;
                Console.WriteLine("Result = {0}", Result);
            }
            catch (Exception ex)
            {
                string filePath = @"C:\Sample Files\Log.txt";
                if (File.Exists(filePath))
                {
                    StreamWriter sw = new StreamWriter(filePath);
                    sw.Write(ex.GetType().Name + ex.Message + ex.StackTrace);
                    sw.Close();
                    Console.WriteLine("There is a problem! Plese try later");
                }
                else
                {
                    //To retain the original exception pass it as a parameter
                    //to the constructor, of the current exception
                    throw new FileNotFoundException(filePath + " Does not Exist", ex);
                }
            }
        }
        catch (Exception ex)
        {
            //ex.Message will give the current exception message
            Console.WriteLine("Current or Outer Exception = " + ex.Message);


            //Check if inner exception is not null before accessing Message property
            //else, you may get Null Reference Excception
            if(ex.InnerException != null)
            {
                Console.WriteLine("Inner Exception = ", ex.InnerException.Message);
            }
        }
    }
}