Question

how to calculate idle time of an application in mfc.

If an application session has been idle for more than 15 minutes how to re-authenticate
session.

Answer 1

You need the “GetLastInputInfo” API.

UINT GetIdleMS()
{
   LASTINPUTINFO li = { 0 };
   li.cbSize        = sizeof(LASTINPUTINFO);
   GetLastInputInfo(&li);
   return GetTickCount() - li.dwTime;
}