Another WM_COPYDATA issue

[Crusader2010]

Hi. Here is some code, i'll write the explanations after:

<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
    Public Structure MsgSTR
        Public code As String
        Public index1 As Integer
        Public index2 As Integer
        Public arr() As Integer
    End Structure

<StructLayout(LayoutKind.Sequential)> _
    Public Structure CopyData
        Public dwData As IntPtr
        Public cbData As Integer
        Public lpData As MsgSTR
    End Structure

Private Declare Auto Function SendMessage Lib "user32" _
     (ByVal hWnd As IntPtr, _
      ByVal Msg As Integer, _
      ByVal wParam As IntPtr, _
      ByVal lParam As CopyData) As Boolean

    Private Declare Auto Function FindWindow Lib "user32" _
     (ByVal lpClassName As String, _
      ByVal lpWindowName As String) As IntPtr

    Private Const WM_COPYDATA As Integer = &H4A

Private Function mesajSMSSTR(ByVal msg As MsgSTR) As Boolean
        Dim ClientWindow As IntPtr
        Dim a() As System.Diagnostics.Process = System.Diagnostics.Process.GetProcesses

        For Each p In a
            If UCase(p.ProcessName) = "SOMEPROCESS" Then
                ClientWindow = p.MainWindowHandle
                Exit For
            End If
        Next
       
        If Not ClientWindow.Equals(IntPtr.Zero) Then

            Dim message As MsgSTR = msg
            Dim data As CopyData

            data.lpData = message
            data.cbData = Marshal.SizeOf(message)

            frmTest.SendMessage(ClientWindow, frmTest.WM_COPYDATA, Me.Handle, data)
            Return True
        Else
            Return False
        End If
End Function

Private Sub cmdSend_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdSend.Click
       
            Dim msg As MsgSTR
            msg.code = Trim(txtCode.Text)
            msg.index1 = CInt(Trim(txtI1.Text))
            msg.index2 = CInt(Trim(txtI2.Text))
            ReDim msg.arr(40)
            For i = 0 To Trim(txtArr.Text).Split(" ").Length - 1
                msg.arr(i) = CInt(Trim(txtArr.Text).Split(" ")(i))
            Next



            If mesajSMSSTR(msg) Then
                MsgBox("Message sent")
            Else
                MsgBox("Message not sent. Process not running.")
            End If
       
End Sub

Basically i have a structure with a string, two 32bit integers and an array of 32bit integers. I need to send this structure using WM_COPYDATA to an application made in VC++ 6.0, from my VB .NET 2008 framework 3.5.

When i execute the code above, only the (first) string is sent. If i comment the lines related to Arr() (both in the structure and in the _click event), only the first 16 characters of my string are being sent.

For testing purposes, the receiving application uses memcopy to get any data that is sent to it and displays it in a messagebox.

I have searched google and these forums a lot for similar problems but everything i tried yielded the same result - the integer values are not sent at all.

If i put 3 strings in my structure instead, only the first is sent. Adding a vbNullString to the end of the first string (MSGSTR.code) results in an empty message box in the receiving application.

Any help is appreciated, thanks.