wm-timechange.md

description	ms.assetid	title	ms.topic	ms.date
A message that is sent whenever there is a change in the system time.	94b5b6f7-04bb-4e0a-848b-e2b31ffc2938	WM_TIMECHANGE message (Winuser.h)	reference	05/31/2018

WM_TIMECHANGE message

A message that is sent whenever there is a change in the system time.

A window receives this message through its WindowProc function.

LRESULT CALLBACK WindowProc(
  HWND hwnd,       // handle to window
  UINT uMsg,       // message identifier
  WPARAM wParam,   // not used; must be zero
  LPARAM lParam    // not used; must be zero
);

Parameters

hwnd

A handle to window.

uMsg

WM_TIMECHANGE identifier.

wParam

Not used; must be zero.

lParam

Not used; must be zero.

Return value

An application should return zero if it processes this message.

Remarks

An application should not broadcast this message, because the system will broadcast this message when the application changes the system time.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	Winuser.h (include Windows.h)

See also

SendMessage