I can't understand how to use SendMessage or PostMessage calls

Question

I need to simulate a keypress in a third party application. Let\'s say I have a C# application that needs to send an \"8\" to the Calculator application. I can\'t use the Se

Answer 1

The solution here helped me but I had to edit it, also it's now shorter:

Also here a usefull list of Virtual Key Codes

        [DllImport("user32.dll")]
        public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("user32.dll")]
        static extern bool PostMessage(IntPtr hWnd, UInt32 Msg, int wParam, int lParam);

        private void button1_Click(object sender, EventArgs e)
        {
            const int WM_SYSKEYDOWN = 0x0104;

            IntPtr WindowToFind = FindWindow(null, "Calculator");

            PostMessage(WindowToFind, WM_SYSKEYDOWN, ((int)Keys.NumPad7), 0);
        }