.NET - How to debug a dll ?

Question

Hi,

I need to debug a class library project that is provided to the main project (an ASP .NET website) as a DLL. For example, I need to put some breakpoints in order to check what's happening during the execution. I tried this : http://msdn.microsoft.com/en-us/library/605a12zt.aspx, unfortunately it didn't work...

Any idea?

Thanks

[EDIT] Yes I have the source code!

Answer 1

If you have the source code, and the .pdb files in your BIN directory, then you can debug through that code. You will need to enable external code debugging however in Visual Studio.

You need to uncheck the "Enable Just My Code" Option.

Tools --> Options --> Debugging --> "Enable Just My Code"

NOTE: This will only work for .Net assemblies

Answer 2

Is this what you're looking for? [Full disclosure: Yes, this is my personal web site]

http://www.gowland.ca/debugging-dlls-in-c (see #2 in the list)

EDIT:

With method #1, you can't watch variables.

With method #2, step #2, if you can't open the project in the same VS instance, you can run the binary of the project (that is, run it outside of VS, but make sure you run the debug version.) and attach the VS debugger to it (Debug -> Attach to Process).

Here are the steps for method #2 so no one has to follow the link:

Attaching a using process to the DLL project This involved hooking the VS debugger into a running process.

1. Open the DLL project in VS.
2. Run an application that uses the DLL. This application can't be run from another instance of VS since the process will already have a debugger attached to it.
3. From here you can add break points and step through the DLL code loaded in VS (although the break point will appear disabled the same as in method 1).