How to print line number where object reference occurred

Question

I need a suggestion regarding Object reference issue. I got this message ExceptionMessage: Object reference not set to an instance of an object. (because some null object) I am printing the stack trace when an error occurs:

 Exception systemException = lastError.GetBaseException();

By using ex.Message I am able to get the method where exception has occurred but I am not getting any information regarding the line (of that method) where exception occurred. I need to know at which line object reference has occurred and which object was null when this exception came.

I'd imagine that the line number would be in the stack trace — Sam I am says Reinstate Monica, Jul 09 '12 at 16:03
I believe [this][1] is a similar question to the one you're asking [1]: http://stackoverflow.com/questions/5817796/how-to-print-out-line-number-during-application-run-in-vb-net — Eric, Jul 09 '12 at 16:06

score 4 · Answer 1 · answered Jul 09 '12 at 16:05

You need the actual stacktrace:

systemException.StackTrace

If you want the line numbers, you will need to do something like this:

StackTrace st = new StackTrace(systemException, true);
StackFrame[] frames = st.GetFrames();

foreach(StackFrame frame in frames)
    frame.GetFileLineNumber();

score 0 · Accepted Answer · answered Jul 09 '12 at 16:05

That line number is pretty much guaranteed to be in the stack trace. If you want to drill down on it, put a try-catch in the large block of code where it might be happening and drop a breakpoint on the catch block, which will allow you to drop down through the InnerExceptions inside of visual studio (if any exist).

Dinesh · Answer 3 · 2012-07-09T16:32:57.957

Maybe this helps

class Program
    {
        static void Main(string[] args)
        {
            try
            {
                string a = null;
                a.ToString();
            }
            catch (Exception ex)
            {
                var s = ex.StackTrace;
                Console.WriteLine(ex.Source);
                int st = s.LastIndexOf("line");
                Console.WriteLine(s.Substring(st, s.Length - st));
            }
        }
    }

Edited :

And yes I just learned, using StrackTrace in the answer posted by EkoostikMartin. I think it is a better answer.

How to print line number where object reference occurred

3 Answers3