Calling a Delphi DLL from C# produces unexpected results

Question

I have a Delphi DLL that I did not write, but need to call from a C# ASP.NET 3.5 app. Here is the function definition I got from the developers:

function Cr         


        

Answer 1

jn is right. The function prototype, as given, cannot be easily called directly from C# as long as it is in Delphi's register calling convention. You either need to write a stdcall wrapper function for it - perhaps in another DLL if you don't have source - or you need to get the people who maintain the function to change its calling convention to stdcall.

Update: I also see that the first argument is a Delphi string. This isn't something that C# can supply either. It should be a PChar instead. Also, it's important to be clear about whether the function is Ansi or Unicode; if the DLL is written with Delphi 2009 (or later), then it is Unicode, otherwise it is Ansi.