@ Plystire
Sorry... I mustn't have explained it well. I'll put it in steps because it's a bit confusing. I don't own DarkBasic, and I know only a little of it, bwcause I considered buying it, so I'll write in pseudocody DarkBasicy code.
1. Include the DLL called "COM Access DLL Test.dll". This is a completely unmanaged DLL, the only kind that DBP can use. This DLL uses COM to call a C# DLL.
2. Add some code similar to this:
Dim COMInteger as Integer
COMInteger = TestInteger()
Print COMInteger
This basically shows whatever the TestInteger function returns.
3. Compile it. Make sure this is compiled with the ExternaliseDLLS option on, and that both included DLLs are put in both the DBP project's directory, and the built executable directory. You'll also need .NET framework 2.0 if you don't already have it.
4. Run the program. If you get 57 on the screen, everything works, and I don't have to learn any other C++ish things. If it doesn't work, I'll give you something else to test.
On a side note, the program included in the zip file just tests the whole thing. I just need to make sure it works in DarkBasic before going any further.