How to use WM_Close in C#?

Question

Can anyone provide me an example of how to use WM_CLOSE to close a small application like Notepad?

Answer 1

Provided you already have a handle to send to.

...Some Class...
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = false)]
static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);

//I'd double check this constant, just in case
static uint WM_CLOSE = 0x10;

public void CloseWindow(IntPtr hWindow)
{
  SendMessage(hWindow, WM_CLOSE, IntPtr.Zero, IntPtr.Zero);
}
...Continue Class...

Getting a handle can be tricky. Control descendant classes (WinForms, basically) have Handle's, and you can enumerate all top-level windows with EnumWindows (which requires more advanced p/invoke, though only slightly).