DLL built on Vista won't run on XP - sort of

[obrienj]

I have only a Vista machine with Visual Studio C++ Express to build a "C" DLL on. The target for the DLL is XP.

And it is a "C" DLL NOT a C++ DLL.

Actually I have two DLLs that I am "converting" at the moment, both compiled on Vista.

One of them, a derivative of the SQLite.DLL, with math and string functions, when copied to XP runs fine.

The other also compiles and runs on Vista, but gets a "-1" error on DLLOpen on XP which tells me nothing but that some error occurred.

BTW, both DLLs are invoked by the exact same AutoIt based ".exe" file which was built and runs on Vista and copied to XP

I have the Visual C++ 2008 Redistributable - x86 installed.

If I look at the failing DLL with PEViewer on XP, it shows all dependencies loaded.

Both use "cdecl" protocol and the DLLCalls in the AutoIt code indicate that.

For the life of me, I can't see the difference in the project properties files between the two DLLs other than the one that works is "Release" and the one that fails is "Debug".

I do know that the SQLite DLL is not s big user directly of the Windows API while the other DLL is.

Oh yes, the failing DLL was originally built on XP with C++ 2005 and also ran on XP. The reason for recompilation was to change a message text.

When I moved my development to Vista, the DLL project was converted by Visual Studio just like all my other "C" and "C++" other projects.

I have had no such problems with C#, Java, AutoIt or any other C++ or C programs including DLLs.

Anyone got any idea of the things I should look at?

Regards,

Jim

Edited January 14, 2010 by obrienj

[obrienj]

This is truly bizarre!

I changed the failing DLL from Debug to Release and it works on XP.

Then again, I've seen stranger things in 50 years working with computers.

Regards,

Jimk

[jchd]

This is truly bizarre!

I changed the failing DLL from Debug to Release and it works on XP.

I find it strange also. I've been building SQLite extensions with VC 2008 recently and never had a problem running them, debug or release. I've now swtich to using gcc for various reasons, but it should work for you as well.

Are you definitely positive this can't be (or have been) a dumb path problem or anything fairly irritating at this level. Don't take it bad, it's just that it _does_ happen!

[monoceres]

Not strange at all. Release mode removes a lot of dependencies and the resulting binary is made so it is going to be as compatible as possible.

Installing VC Redist 2008 fixes most problems (or statically link your dll).

[jchd]

Installing VC Redist 2008 fixes most problems (or statically link your dll).

I see. I installed VC 2008 only fairly recently and it's likely the download I used already had the patch included.

That, or it's also possible that I wasn't using enough MS library functions for the fix to be required in my case.

Generally, SQLite extension don't need that much external functions.