ExitThreadDWORD

ExitThreadDWORD refers to the use of the Windows API function ExitThread when terminating a thread and specifying a 32‑bit exit code. In the Windows programming model, each thread can terminate by calling ExitThread, which accepts a single parameter of type DWORD that signifies the thread’s exit status. The exit code is a 32‑bit unsigned integer that can be retrieved by the thread‑creating process or by other threads that handle termination notifications. It is commonly used to communicate success, failure, or specific status information back to the caller.

The prototype for ExitThread is declared in the Windows header files as follows: VOID ExitThread(DWORD dwExitCode). The function does not return to the caller; instead, it terminates the current thread. The value passed as dwExitCode is stored internally in the thread’s ExitCode field. Later, a caller can retrieve it by calling GetExitCodeThread on the thread handle or by examining the status of the thread after a WaitForSingleObject or WaitForMultipleObjects call returns.

Typical use cases involve spawning worker threads that perform a computation and then exit with a status code indicating whether the computation succeeded, failed, or encountered an error condition. The value can also be used for debugging or logging purposes. Because ExitThread immediately terminates the thread, it should be called only after all necessary cleanup operations are performed, or alternatively by using the higher‑level FinishThread pattern that performs cleanup before calling ExitThread.

Limitation: The exit code is only retrievable after the thread has finished; attempting to read the code before termination can yield undefined results. For cooperative termination, threads often poll a shared flag or use an event mechanism in addition to ExitThread. This approach avoids potential issues with abrupt termination.