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4/8/2010

This function places a message in the message queue associated with the thread that created the specified window and then returns without waiting for the thread to process the message. Messages in a message queue are retrieved by calls to the GetMessageor PeekMessagefunction.

Syntax 

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

Parameters

hWnd

[in] Handle to the window whose window procedure is to receive the message. Two values have special meanings.

Value Description

HWND_BROADCAST

The message is posted to all top-level windows in the system, including disabled or invisible unowned windows, overlapped windows, and pop-up windows. The message is not posted to child windows.

NULL

The function behaves like a call to PostThreadMessagewith the dwThreadIdparameter set to the identifier of the current thread.
Msg

[in] Specifies the message to be posted.

wParam

[in] Specifies additional message-specific information.

lParam

[in] Specifies additional message-specific information.

Return Value

Nonzero indicates success. Zero indicates failure. To get extended error information, call GetLastError.

Remarks

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

If you send a message in the range below WM_USER to the asynchronous message functions ( PostMessageand SendNotifyMessage), 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.

Windows Embedded CE does not support all the messages the Windows-based desktop platforms support.

Requirements

Header winuser.h
Library coredll.lib
Windows Embedded CE Windows CE 1.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also