How to marshal a struct into a UInt16 Array

Question

I know that you can use code like this to marshal a structure into a byte array:

public static byte[] StructureToByteArray(object obj)
{
    int len = Marshal.SizeOf(obj);
    byte[] arr = new byte[len];
    IntPtr ptr = Marshal.AllocHGlobal(len);
    Marshal.StructureToPtr(obj, ptr, true);
    Marshal.Copy(ptr, arr, 0, len);
    Marshal.FreeHGlobal(ptr);
    return arr;
}

But how do you marshal a structure into an array containing 16 bit words instead of bytes?

public static UInt16[] StructureToUInt16Array(object obj)
{
    // What to do?
}

Answer 1

Any reason not to marshal into a byte array and then use Buffer.BlockCopy? That would be the simplest approach, I'd say. Admittedly you do have to do appropriate copying, so it's less efficient, but I don't think you'll find a much simpler way.

Answer 2

The Unsafe and the Safe way to do this:

static UInt16[] MarshalUInt16(Object obj)
    {
        int len = Marshal.SizeOf(obj);

        IntPtr ptr = Marshal.AllocHGlobal(len);
        Marshal.StructureToPtr(obj, ptr, true);

        UInt16[] arr = new UInt16[len / 2];

        unsafe
        {
            UInt16* csharpPtr = (UInt16*)ptr;

            for (Int32 i = 0; i < arr.Length; i++)
            {
                arr[i] = csharpPtr[i];
            }
        }

        Marshal.FreeHGlobal(ptr);
        return arr;
    }

    static UInt16[] SafeMarshalUInt16(Object obj)
    {
        int len = Marshal.SizeOf(obj);
        byte[] buf = new byte[len];
        IntPtr ptr = Marshal.AllocHGlobal(len);
        Marshal.StructureToPtr(obj, ptr, true);
        Marshal.Copy(ptr, buf, 0, len);
        Marshal.FreeHGlobal(ptr);

        UInt16[] arr = new UInt16[len / 2];

        //for (Int32 i = 0; i < arr.Length; i++)
        //{
        //    arr[i] = BitConverter.ToUInt16(buf, i * 2);
        //}

        Buffer.BlockCopy(buf, 0, arr, 0, len);

        return arr;
    }

Updated to reflect the wisdom of others.