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 SendNotifyMessage

The SendNotifyMessage function sends the specified message to a window or windows. 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.

Syntax

    BOOL SendNotifyMessage(
        HWND hWnd,
        UINT Msg,
        WPARAM wParam,
        LPARAM lParam
    );

Parameters

• hWnd
  [in] 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
  [in] Specifies the message to be sent.
• wParam
  [in] Specifies additional message-specific information.
• lParam
  [in] Specifies additional message-specific information.

Return Value

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 cannot 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.

The system only does marshalling for system messages (those in the range 0 to (WM_USER-1)). To send other messages (those >= WM_USER) to another process, you must do custom marshalling.

Windows 95/98/Me: SendNotifyMessageW is supported by the Microsoft Layer for Unicode (MSLU). To use this, you must add certain files to your application, as outlined in Microsoft Layer for Unicode on Windows 95/98/Me Systems .

Function Information

• Minimum DLL Version user32.dll
• Header Declared in Winuser.h, include Windows.h
• Import library User32.lib
• Minimum operating systems Windows 95, Windows NT 3.1
• Unicode Implemented as ANSI and Unicode versions.

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Notebook exported on Monday, 7 July 2008, 18:56:50 PM Eastern Daylight Time