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Struct to ByteArray related question
f#

Hey guys, the byte array that it generates seems to be missing a character from the string, it outputs in HEX: 61616100 when it should be displaying 61616161 in the bytearray... Am I missing something?

Here is the code I used...

(I took out the arrow brackets inside the [ ]s since it wasn't showing up...)

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[Struct] 
[StructLayout(LayoutKind.Sequential)]
type PacketTest =

    [MarshalAs( UnmanagedType.ByValTStr, SizeConst=4 )]
    val mutable a : string

let mutable pt = PacketTest()
pt.b (leftarrowbracket)- "aaaa"

let size = Marshal.SizeOf(typeof)
let bytearray : byte[] = Array.create size (byte 0)
let ptr = Marshal.AllocHGlobal(size)
Marshal.StructureToPtr(pt, ptr, true)
Marshal.Copy(ptr, bytearray, 0, size )
Marshal.FreeHGlobal(ptr)

let ByteToHex bytes = 
    bytes 
    |> Array.map (fun (x : byte) -> System.String.Format("{0:X2}", x))
    |> String.concat System.String.Empty

let byteStr = ByteToHex bytearray

printfn "%s" byteStr

Thanks....

.

In .NET strings are always terminated with character '\0' (see the cryptic comment about VB 6.0 on the description of UnmanagedType.ByValTStr) - if you want to be able to see 4 arbitrary characters after marshalling, then I believe you'll need to use a character array instead of a string.

By on 4/23/2010 8:35 PM ()

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