Delphi dll and c# pinvoke declaration

Question

I am wondering if someone could check my c# dllimport declaration for a dll compiled with Delphi XE2. Calling this dll from a ISAPI wrapper dll works fine but I am having no luck calling it from a c# asp.net app.

The Delphi procedure is defined as:

procedure ExecuteService(const RequestJSON :PWideChar; out ResponseJSON :Pointer; out ResponseJSONSize :Integer; out ResponseContent :Pointer; out ResponseContentSize :Integer); stdcall;

and the c# declaration is:

 [DllImport("services.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Unicode)]
        public static extern void BIExecuteService(
            String requestJSON,
            out IntPtr reposnseJSON,
            out int reposnseJSONSize,
            out IntPtr reposnseContent,
            out int reposnseContentSize
        );

Sometimes it works but mostly it gives a System.AccessViolationException.

I have been trying to solve this for days, do the declarations look correct?

Edit: Attaching to the IISExpress process in Delphi XE2 the error seems to occur in clr.dll. Maybe my library is corrupting something but I have no idea how to find out where!

Thanks,

AJ

Problem liable to be in how you call the function. You didn't show that. Ideally, you would show both Delphi and C# calling code. As asked, the question is trivial to answer, and the answer is probably of no use to you. This is a classic example of the XY problem. — David Heffernan

David Heffernan David Heffernan · Accepted Answer · 2013-08-11T18:14:58

Your p/invoke declaration is correct. Your problems lie elsewhere.

Delphi dll and c# pinvoke declaration

1 Answers