c# Visual Studio appears to follow an incorrect code path

Question

Below is a small snippet taken from a fairly large app to simplify my question. I submitted this question before, but my poor wording caused it to be closed before I managed to edit my question.

This is the current snippet to which I have added some logging lines.

int i = 0; 
Console.WriteLine("Before brackets");
if (i < 0) 
{ 
      Console.WriteLine("Inside brackets");
      return MyArray[i]; 
} 

When I debug with VS I see:

i set to 0
if evaluates as false (when I hover over it in VS) 
In Output: Before brackets

Then the debugger steps inside the brackets and the return MyArray[i] is executed however I do not see Inside brackets in the output by the time I have stepped through to the return MyArray[i] line.

This behaviour is obviously (to me) wrong and I wondered if anyone else had encountered something like this.

I am on a Windows XP, 64bit machine , with VS10 and .Net4.0.

Moon

ADDITIONAL1

I have been asked by Henk to provide a "console App" which I have done below. HOWEVER, as I would suspect, it does NOT SHOW the issue. I believe there is something else (threads?) causing me an in issue in my real app - and I obviously can post that. I realise I am not giving you a clearly defined problem - if I could, I would. That is why I am asking this question - incase it strikes a cord with somebody having something similar. For good order, here is console version which DOES NOT exhibit the problem. I have a feeling putting it on here will add to the confusion...

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

namespace ConsoleApplication2
{
    class Program
    {
        static string[] Mods = new string[] { "Cat", "Dog", "Geek" };

        static void Main(string[] args)
        {
            string t = "Geek";
            Console.WriteLine("Answer: " + FindD(t));

        }

        public static string FindD(string ModelFullName)
        {
            int ix = Array.IndexOf<string>(Mods, ModelFullName);

            Console.WriteLine("ix: " + ix + " = " + (ix < 0).ToString());
            if (ix < 0)
            {
                Console.WriteLine("2ix: " + ix + " = " + (ix < 0).ToString());
                Error.Process(ErrorLevel.Critical, "ModelName not found: " + ModelFullName);
            }
            try
            {

                return Mods[ix];
            }
            catch (Exception)
            {
                Error.Process(ErrorLevel.Critical, "Could not point to Mod for: " + ModelFullName);
            }

            return null;
        }

        enum ErrorLevel { Note, Critical };
        class Error
        {
            public static void Process(ErrorLevel EL, string message)
            {
                if (EL == ErrorLevel.Critical)
                {
                    throw new Exception("Critical error: " + GetStackTrace() + message);
                }
            }

            public static string GetStackTrace()
            {
                StackTrace stackTrace = new StackTrace();           // get call stack
                StackFrame[] stackFrames = stackTrace.GetFrames();  // get method calls (frames)

                string st = "";
                // write call stack method names
                for (int i = 6; i > 1; i--)
                {
                    StackFrame stackFrame = stackFrames[i];
                    st = st + stackFrame.GetMethod().Name + "/";
                }

                return st;
            }
        }
    }
}

ADDITIONAL 2

It seems that my issue is NOT one of the execution path going a wrong route ONLY VS debugger. ie It appears as if I am going inside the brackets, because debugger steps on the last statement, but the results I actually get appear correct.

Answer 1

I have managed to resolve the issue after a tip I found from a google web search. It seems I was running the debugger in "Optmise Code" mode. This is something I checked early on, BUT what I didn't spot wad that although I had this option deselected for Debug Mode - I had "Release" selected in the Standard Toolbar. When I switched to " Debug " the issue went away.

Answer 2

I must be missing something, but this is quite logic ?

• i is set to zero.
  • i is not less than zero.
  • Inside brackets is NOT outputted.

This is logical, isn't it ? Step through the code using the debugger. You'll see it makes sense.

Answer 3

Are you sure your if statement isn't as follows:

if (i < 0)
    Console.WriteLine(...);
    return MyArray(i);

Note the misleading indentation and the lack of brackets.

Answer 4

If i = 0 then i < 0 is false. If you set your condition to i <= 0 , then it executes the condition.