Question

i have two list want to compare and then filter it.
so if list1 contains 1,2,3,4 and list2 2,4 i want to filter list and leave only 1 and 3

HProDataContext db = new HProDataContext();


        List<int> _AllRoomsID = (from d in db.rooms select d.id).ToList();
        List<int> _ClosedRoomsID = (from d in db.checkinouts select d.roomid).ToList();

        for (int i = 0; i < _ClosedRoomsID.Count; i++)
        {
            if (_AllRoomsID.Contains(_ClosedRoomsID[i]) == true)
            {

            }
        }

Answer 1

var OpenRooms = AllRoomsID.Except(ClosedRoomsID);

Or, if you don’t want an IEnumearble:

List<int> OpenRooms = AllRoomsID.Except(ClosedRoomsID).ToList();