c# syntax question

Question

I am P/Invoking several functions. Looking at an atricle on how to do this I ran across the following syntax in the function declaration: [DllImport (kernel32.dll)] internal static extern Boolean SetCommState(IntPtr hFile [In] ref DCB lpDCB); and [DllImport(kernel32.dll)] internal static extern Boolean ReadFile(IntPrt hFile [Out] byte [] lpBuffer UInt32 nNumberOf BytesRead IntPtr lpOverlapped); My question is about the [IN] and the [Out] syntax. What do they mean?? Thanks Keith Stallings

developer 0 · Answer

The out is similar to the out modifiers in function declarations. It specifies that the parameter is passed by reference and must be assigned by the method being called. i.e. static void Split (string name out string firstNames out string lastName) i'm not sure about the IN.