How can I programmatically generate keypress events in C#?

The question is tagged WPF but the answers so far are specific WinForms and Win32.

To do this in WPF, simply construct a KeyEventArgs and call RaiseEvent on the target. For example, to send an Insert key KeyDown event to the currently focused element:

var key = Key.Insert;                    // Key to send
var target = Keyboard.FocusedElement;    // Target element
var routedEvent = Keyboard.KeyDownEvent; // Event to send
     target.RaiseEvent(
  new KeyEventArgs(
    Keyboard.PrimaryDevice,
    PresentationSource.FromVisual(target),
    0,
    key)
  { RoutedEvent=routedEvent }
);

This solution doesn’t rely on native calls or Windows internals and should be much more reliable than the others. It also allows you to simulate a keypress on a specific element.

Note that this code is only applicable to PreviewKeyDown, KeyDown, PreviewKeyUp, and KeyUp events. If you want to send TextInput events you’ll do this instead:

var text = "Hello";
var target = Keyboard.FocusedElement;
var routedEvent = TextCompositionManager.TextInputEvent;

target.RaiseEvent(
  new TextCompositionEventArgs(
    InputManager.Current.PrimaryKeyboardDevice,
    new TextComposition(InputManager.Current, target, text))
  { RoutedEvent = routedEvent }
);

Also note that:

• Controls expect to receive Preview
  events, for example PreviewKeyDown
  should precede KeyDown

• Using target.RaiseEvent(…) sends the event directly to the target
  without meta-processing such as
  accelerators, text composition and
  IME. This is normally what you want.
  On the other hand, if you really do
  what to simulate actual keyboard keys
  for some reason, you would use
  InputManager.ProcessInput() instead.