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527

answers:

2

I am using C# and VS2010.

When I use OutputDebugString to write debug information, should it show up in the output window? I can see the output from OutputDebugString in DebugView, but I thought I would see it in Visual Studio's Output window. I have looked under Tools->Options->Debugging->General and the output is NOT being redirected to the Immediate window. I have also looked under Tools->Options->Debugging->Output Window and all General Output Settings are set to "On". Finally, I have used the drop-down list in the Output window to specify that Debug messages should appear.

If I change Tools->Options->Debugging->General to redirect the output to the Immediate window, the OutputDebugString messages do not appear in the immediate window.

Here is my entire test program:

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

namespace OutputDebugString
{
  class Program
  {
    [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
    public static extern void OutputDebugString(string message);

    static void Main(string[] args)
    {
      Console.WriteLine("Main - Enter - Console.WriteLine");
      Debug.WriteLine("Main - Enter - Debug.WriteLine");
      OutputDebugString("Main - Enter - OutputDebugString");
      OutputDebugString("Main - Exit - OutputDebugString");
      Debug.WriteLine("Main - Exit - Debug.WriteLine");
      Console.WriteLine("Main - Exit - Console.WriteLine");
    }
  }
}

If I run within the debugger, the Debug.WriteLine output does show up in the output window, but the OutputDebugString output does not.

If I run from a console window, both Debug.WriteLine and OutputDebugString show up in DebugView.

Why doesn't the OutputDebugString output ever show up in the output window?

Ultimately, my intent is not to write a lot of debug output with OutputDebugString, rather I will use System.Diagnostics or NLog or something similar. I am just trying to find out, if I configure a logging platform to write to OutputDebugString, will the output be visible from within the debugger.

Edit: I went back to my original program (not the simple test above) which uses TraceSources and TraceListeners configured via the app.config file. If I configure the trace sources to write to the System.Diagnostics.DefaultTraceListener (which is documented as writing to OutputDebugString), then the trace source output DOES go to the debug window. However, lines that write directly with OutputDebugString (such as in my simple example) DO NOT go to the debug window. Also, if I use a different TraceListener that writes to OutputDebugString (I got one from Ukadc.Diagnostics at codeplex), that output DOES NOT go to the debug window.

One note about the Ukadc.Diagnostics trace listener... Ukadc.Diagnostics contains some trace listeners that allow for custom formatting of output (similar to the formatting that is available in log4net, NLog, and LAB). So, with "only" a dependency on Ukadc.Diagnostics one can use "standard" .NET diagnostic logging but can get some advanced features (like the output formatting) without becoming dependent on a possibly much larger platform. In this case, I could use the Ukadc.Diagnostics OutputDebugStringTraceListener to write logging output to the debug window in the same format (if desired, or a different format) as it would be if written to a file.

Note that I have seen these questions but they did not provide a working solution: here and here

A: 

It might be showing in the "Immediate Window" instead due to a setting:

  • Go to Tools/Options/Debugging/General. Uncheck "Redirect all Output Window text to the Immediate Window"

Or somethig like that.

Michael Burr
Thanks. I looked and that option is not checked. If I do check it, my output also does not appear in the Immediate window.
wageoghe
+2  A: 

You had me going on this question for a while. No way! Way.

Project + Properties, Debug tab, check "Enable unmanaged code debugging".

Hans Passant
That was it exactly! I changed that setting in my sample program and then back in my original program and it fixed in both places.Accepting this answer because it is right!
wageoghe