SendNotifyMessage

The SendNotifyMessage function sends the specified message to a window. If the window was created by the calling thread, SendNotifyMessage calls the window procedure for the window and does not return until the window procedure has processed the message. If the window was created by a different thread, SendNotifyMessage passes the message to the window procedure and returns immediately; it does not wait for the window procedure to finish processing the message.

BOOL SendNotifyMessage(
  HWND hWnd,      // handle of destination window
  UINT Msg,       // message to send
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
);
 

Parameters

hWnd

Handle to the window whose window procedure will receive the message. If this parameter is HWND_BROADCAST, the message is sent to all top-level windows in the system, including disabled or invisible unowned windows, overlapped windows, and pop-up windows; but the message is not sent to child windows.

Msg

Specifies the message to be sent.

wParam

Specifies additional message-specific information.

lParam

Specifies additional message-specific information.

Return Values

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

If you send a message in the range below WM_USER to the asynchronous message functions (PostMessage, SendNotifyMessage, and SendMessageCallback), its message parameters can not include pointers. Otherwise, the operation will fail. The functions will return before the receiving thread has had a chance to process the message and the sender will free the memory before it is used.

Applications that need to communicate using HWND_BROADCAST should use the RegisterWindowMessage function to obtain a unique message for inter-application communication.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Requires version 1.0 or later.
  Header: Declared in winuser.h.
  Import Library: Use user32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT.

See Also

Messages and Message Queues Overview, Message and Message Queue Functions, PostMessage, PostThreadMessage, RegisterWindowMessage, SendMessage SendMessageCallback, SendNotifyMessage