>In coping data between managed and native code, I make use of the Marshal
>class methods, ReadInt32, Copy, StructureToPtr, etc. However, I also want to
>copy Double and Single values, but given that there's is no ReadSingle and
>ReadDouble, what's the best way to do the copy?

"Mattias Sjögren" <mattias.dont.want.spam@mvps.org> wrote in message
news:ub9GOiZLIHA.484@TK2MSFTNGP06.phx.gbl...
>
>>In coping data between managed and native code, I make use of the Marshal
>>class methods, ReadInt32, Copy, StructureToPtr, etc. However, I also want
>>to
>>copy Double and Single values, but given that there's is no ReadSingle and
>>ReadDouble, what's the best way to do the copy?
>
> A couple of different options with varying performance.
>
> - Use Marshal.Copy to a single[1] or double[1].
>
> - Use Marshal.PtrToStructure. I believe it handles simple types as
> well. If not you can use a dummy wrapper type:
>
> struct YourDouble { public double d; }
>
> - For doubles, use Marshal.ReadInt64 followed by
> BitConverter.Int64BitsToDouble.
>
> - Use the CopyMemory windows API.
>
> [DllImport("kernel32.dll")]
> static extern void RtlMoveMemory(out double dest, IntPtr src, int cb);
>
> - If you use a language with pointer support (C# with unsafe code or
> C++) you can cast to a real double* or single* and simply dereference
> it.
>
>
> Mattias
>
> --
> Mattias Sjögren [C# MVP] mattias @ mvps.org
> http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
> Please reply only to the newsgroup.