I want to develop an application for a RFID system. Basically for identification, e-wallet, etc. One of the problem is, the SDK for the equipment requires me to give the method a memory address for the var instead of the var itself for the response. They gave me an example in VB6, which they use VarPtr or IntPtr, and as far as i know C# doesn't have that (or is there... ). I tried to use the interop , but even though i can get the memory address then it changes the next time i check. Is there a method to call to put that var at static memory location