ResetEvent function (synchapi.h)

Sets the specified event object to the nonsignaled state.


BOOL ResetEvent(
  [in] HANDLE hEvent


[in] hEvent

A handle to the event object. The CreateEvent or OpenEvent function returns this handle.

The handle must have the EVENT_MODIFY_STATE access right. For more information, see Synchronization Object Security and Access Rights.

Return value

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.


The state of an event object remains nonsignaled until it is explicitly set to signaled by the SetEvent or PulseEvent function. This nonsignaled state blocks the execution of any threads that have specified the event object in a call to one of the wait functions.

The ResetEvent function is used primarily for manual-reset event objects, which must be set explicitly to the nonsignaled state. Auto-reset event objects automatically change from signaled to nonsignaled after a single waiting thread is released.

Resetting an event that is already reset has no effect.


Requirement Value
Minimum supported client Windows XP [desktop apps | UWP apps]
Minimum supported server Windows Server 2003 [desktop apps | UWP apps]
Target Platform Windows
Header synchapi.h (include Windows.h on Windows Server 2003, Windows Vista, Windows 7, Windows Server 2008 Windows Server 2008 R2)
Library Kernel32.lib
DLL Kernel32.dll

See also


Event Objects




Synchronization Functions