SendMessage Return Key and Text to WindowHandle in C#

Question

I have searched google on this topic for hours and I am slightly confused. I want to send key strokes to fill in text fields and simulate press of the enter key using c#.

So far I have:

class Program
{

    static void Main(string[] args)
    {
        Process p = Process.Start("File.exe");
        p.WaitForInputIdle();
        IntPtr hWnd = p.MainWindowHandle;
        Command.SendMessage(hWnd,/* */);
    }
}

public class Command
{
    [DllImport("User32.dll")]
    public static extern int SendMessage(IntPtr hWnd, uint Msg, uint wParam, uint lParam);

    public void sendReturn(IntPtr hWnd)
    {
           // do something cool here
    }
}

Is there an easier way to do this?

Answer 1

Use PostMessage instead of send message

Usage:

 [DllImport("User32.Dll")]
         public static extern Int32 PostMessage(IntPtr hWnd, int msg, int wParam, int lParam);

const int WM_KEYDOWN = 0x0100;
const int VK_TAB = 0x09;

 PostMessage(process.MainWindowHandle, WM_KEYDOWN, VK_TAB, 1);