It ends up that calling 32bit DLLs from 64bit code is non-trivial in Windows. One trick is to build a 64bit serializing/marshaling wrapper around your 32bit code. The other trick is to avoid using 64bit code and stick to using 32bit code to call 32bit DLLs. This second approach is what I did.

So, the issue here is not Clarion specific, but merely a problem with using mixed binary DLLs (win32/win64)

Hope this saves someone else some grief.

As for your comment, I’m afraid the application I support is Clarion 5 based and won’t be moving, so I’ve not attempted a Clarion 7.1 function export.

If I were giving advice, I’d say, try something ultra simple (no parameters) and returns a LONG. See if you can get that to work, then make a more complicated example. Good luck.

I’m trying to tackle the task of creating and exporting functions with Clarion via DLLs. I have Clarion 7.1 and many items have seemed to change from the version you used for this article! Do you have any experience creating DLLs with C7.1 and then calling them from C/python/perl/etc?