Hi,

I am trying to pass structure in LParam of SendMessage API. I could
not able to get the value in called window.The code and declaration is
as below:

//Class A
//********

[DllImport("User32.Dll" , CharSet=CharSet.Auto)]
private static extern long SendMessage(
    IntPtr hWnd,      // handle to destination window
    UInt32 Msg,       // message
    UInt32 wParam,  // first parameter
    ref PassingItem lParam   // second parameter
);

[ StructLayout( LayoutKind.Sequential, CharSet=CharSet.Auto )]
public struct PassingItem
{
    public long  MSISDN;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string VarifiedStatus;
}

public const int WM_USER = 0x0400;
public const int MSG_COMMAND_OPEN = WM_USER + 200;

PassingItem PI;

PI.MSISDN = 123;
PI.VarifiedStatus = "Varified";

SendMessage ((IntPtr)hwnd, MSG_COMMAND_OPEN, 0, ref PI);

//Class B
//*******
public const int WM_USER = 0x0400;
public const int MSG_COMMAND_OPEN = WM_USER + 200;

public struct PassingItem
{
    public long  MSISDN;
    public string VarifiedStatus;
}

protected override void WndProc(ref Message m)
{
       if(m.Msg == MSG_COMMAND_OPEN)
    {
    PassingItem PI = (PassingItem)Marshal.PtrToStructure((IntPtr)m.LParam,typeof(PassingItem));

       //value trying to display
       //************************
    MessageBox.Show(PI.MSISDN.ToString());
    }
    else
    {
        base.WndProc(ref m);
    }
}

In the Messagebox it showing 0 value for MSISDN, which is not correct.
Could anybody let em know ASAP what is the problem in my code

Thanks,

Anand