Making value-type arrays in c#

Question

I'm transfering data between c++ and c# and I really need to have value-type arrays or list to pass the data directly. I don't mind them being a const expression. Is there a way to have an array which would behave like a c# struct or like a c++ std::array?

Edit: In the worst case i can use std::vector but i would prefer std::array because i really care about performance

Answer 1

If you're talking about arrays of primitive types (byte, int, etc.) then marshalling between C# and C++ is quite simple using fixed:

        unsafe
        {
            byte[] arr = new byte[1024];
            fixed (byte* nativeArray = arr)
            {
                IntPtr ptr = (IntPtr)nativeArray;
                // Pass ptr directly to C++ and use as an unsigned char*
            }
        }

Note this requires use of the unsafe option when compiling.

The same works for int, uint, short, ushort, float, double, long, and ulong.

You MUST use the pointer on the C++ side immediately and either copy it to a native buffer or be done with it before returning. The point of fixed is to make sure the memory isn't GC'd or moved while control is inside the fixed block.