Hi everybody,

I am wondering if anyone of you has experience making C# dll to be accessible from VFP using DllExport utility. In particular, I am interested in passing parameters by reference.

I made a simple function in C#

[DllExport("CheckParamsByRef", System.Runtime.InteropServices.CallingConvention.StdCall)]
        /// <summary>
        /// CheckParamsByRef
        /// <param name="test">The string to return by reference</param>
        public static int CheckParamsByRef(ref String test)
        {
            test = "Hello from C#";
            return 1;
        }

and try to call it from VFP

DECLARE integer CheckParamsByRef IN "MyDLL x86.dll" ;
    string @ 
ReturnValueText = ""
    ? CheckParamsByRef(@ReturnValueText)
    ? 'ReturnValueText: ' + ReturnValueText

On the ? CheckParamsByRef call I'm getting exception from DLL.

Does it mean we can not use DllExport and passing parameters by reference? Is there any way around the problem?

Thanks in advance.