06 September, 2023

Creating an API (contract) for your own DLL

Or: don't create your own DLLs without reading this article!

This article is not about EurekaLog, but about writing your own DLLs in general. This article is based on questions on the forums: "How do I return a string from a DLL?", "How do I pass and return an array of records?", "How do I pass a form to a DLL?".

So that you do not spend half your life figuring it out - in this article I will bring everything on a silver platter.

Important note: the article must be read sequentially. Code examples are given only as examples: the code of examples is added with new details at each step of the article. For example, at the very beginning of the article there is no error handling, "classic" methods are used (such as using GetLastError, the sdtcall convention, etc.), which are replaced by more adequate ones in the course of the article. This is done for the reason that "new" ("unusual") designs do not raise questions. Otherwise, with each example, one would have to insert a note like: "this is discussed in that paragraph below, but that - in this one here." In any case, at the end of the article there is a link to the sample code written by taking into account everything said in the article. You can just grab it and use it. And the article explains why it is created the way it is. If you are not interested in "why" - scroll to the end to the conclusion and find a link to download the example.