CancelWaitableTimer

The CancelWaitableTimer function sets the specified "waitable" timer to the inactive state.

BOOL CancelWaitableTimer(
  HANDLE hTimer  // handle to a timer object
);
 

Parameters

hTimer

Handle to the timer object. The CreateWaitableTimer or OpenWaitableTimer function returns this handle.

Return Values

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

The CancelWaitableTimer function does not change the signaled state of the timer. It stops the timer before it can be set to the signaled state and cancels outstanding APCs. Therefore, threads performing a wait operation on the timer remain waiting until they time out or the timer is reactivated and its state is set to signaled. If the timer is already in the signaled state, it remains in that state.

To reactivate the timer, call the SetWaitableTimer function.

QuickInfo

  Windows NT: Requires version 4.0 or later.
  Windows: Requires Windows 98 or later.
  Windows CE: Unsupported.
  Header: Declared in winbase.h.
  Import Library: Use kernel32.lib.

See Also

Synchronization Overview, Synchronization Functions, CreateWaitableTimer, OpenWaitableTimer, SetWaitableTimer