RegisterWindowMessage

This function defines a new window message that is guaranteed to be unique throughout the system. The returned message value can be used when calling the SendMessage or PostMessage function.

UINT RegisterWindowMessage( 
LPCTSTR lpString ); 

Parameters

• lpString
  Long pointer to a null-terminated string that specifies the message to be registered.

Return Values

A message identifier in the range 0xC000 through 0xFFFF indicates that the message is successfully registered. Zero indicates failure. To get extended error information, call GetLastError.

Remarks

The RegisterWindowMessage function is typically used to register messages for communicating between two cooperating applications.

If two different applications register the same message string, the applications return the same message value. The message remains registered until the session ends.

Only use RegisterWindowMessage when more than one application must process the same message. For sending private messages within a window class, an application can use any integer in the range WM_USER through 0x7FFF. (Messages in this range are private to a window class, not to an application. For example, predefined control classes such as BUTTON, EDIT, and LISTBOX may use values in this range.)

Requirements

Runs on	Versions	Defined in	Include	Link to
Windows CE OS	2.0 and later	Winuser.h

Note   This API is part of the complete Windows CE OS package as provided by Microsoft. The functionality of a particular platform is determined by the original equipment manufacturer (OEM) and some devices may not support this API.

See Also

GetLastError, PostMessage, SendMessage

 Last updated on Tuesday, July 13, 2004

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