private List<Int32> CheckHand(List<Entities.GamePlayerCard> cards, List<Int32> cardIDs) { List<Int32> missingIds = new List<int>(); Int32 indexOf = -1; foreach (Int32 cardID in cardIDs) { indexOf = cards.FindIndex(x => x.CardID == cardID); if (indexOf < 0) { missingIds.Add(cardID); } } return missingIds; }