VS2008/2010 debugger changes application behavior

I have a very simple Delphi 2010 dll that I load from a Visiual Studio 2008 C ATL console application (MVF GUI app does not work either). When I debug the console app from the IDE directly - no break points - the output from the application is not correct but when I run the app directly or if I attach to the process with the debugger then it works 100%. Debugging the same dll from a Delphi console app (i.e. running it from the IDE) also works.

The VS debugger seems to break the app depending on how you run it. VS开发者_运维问答2010 does the same!

I have made 100% sure - several times! - that the data types and calling convention of the dll exports and those in the console app match. I can go into more detail but I don't want to confuse the matter with what may be irrelevant information. Please tell me if I have to go into the specifics of the code if what I have offered is not enough.

Has anyone experienced this sort of thing and know how to fix it?

I've got similar problem once (different behavior in IDE/debugger and in standalone application). It turned out, that I've checked the value of unset variable. Debugger allocated it (always!) in previously used block of memory, such that the value was not empty and the application worked correctly (because only the conditional block was erroneous). However, OS sometimes put the application in empty memory block (filled with 0s), the condition failed and application crashed.

Maybe this is the issue? Try using OutputDebugString()'s to track down values of variables during the library runtime. Without some source code I believe, that it's not easy to say, what might be the reason.

Best regards -- Spook.