The WaitMessage function yields control to other threads when a thread has no other messages in its message queue. The WaitMessage function suspends the thread and does not return until a new message is placed in the thread's message queue.
BOOL WaitMessage(VOID)
This function has no parameters.
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.
Note that WaitMessage does not return if there is unread input in the message queue after the thread has called a function to check the queue. This is because functions such as PeekMessage, GetMessage, GetQueueStatus, WaitMessage, MsgWaitForMultipleObjects, and MsgWaitForMultipleObjectsEx check the queue and then change the state information for the queue so that the input is no longer considered new. A subsequent call to WaitMessage will not return until new input of the specified type arrives. The existing unread input (received prior to the last time the thread checked the queue) is ignored.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in winuser.h.
Import Library: Use user32.lib.
Messages and Message Queues Overview, Message and Message Queue Functions, GetMessage, PeekMessage