help! how can I rewrite struct with union in C#?

[Li kai Liu Angus]

Hi, In C or C++,some structures are defined with union. How can we rewrite these structure in C# so that we can use them as parameters and pass them into API functions? And, What's the correspondent type in C# to PVOID type in C? Thanks in advance! Angus Liu

[Rama Krishna Vavilala]

ykliu wrote: In C or C++,some structures are defined with union. How can we rewrite these structure in C# so that we can use them as parameters and pass them into API functions? e.g. union U { int x; int y; } can be written in C# as [StructLayout(LayoutKind.Explicit)] class U { [FieldOffset(0)] int x; [FieldOffset(0)] int y; } ykliu wrote: And, What's the correspondent type in C# to PVOID type in C? There are two equivalents of PVOID in C# 1. void* this is when you are using C# pointers. Something which you should never do. 2. IntPtr this is used to encapsultae unmanaged pointers. Use this in conjunction with Marshal.StructureToPtr, Marshal.AllocCoTaskMem etc. functions. Look up all the functions in Marshal class it would be very helpful.

[Li kai Liu Angus]

Hi Rama, Thank you very much, though, I don't understand all of them, especially the Marshal part. I will keep reading some document before asking another question. Angus Liu