public string CountMyFoodsWithSameIdAsAppFoods(string userId) { try { int count = 0; List <string> appFoods = f.LoadFoodsId(); List <string> myFoods = LoadMyFoodsId(userId); if (myFoods != null) { if (myFoods.Count > 0) { foreach (string id in myFoods) { if (appFoods.Contains(id)) { count++; } } } } return(JsonConvert.SerializeObject(string.Format("there are {0} foods with the same id", count), Formatting.None)); } catch (Exception e) { L.SendErrorLog(e, null, userId, "MyFoods", "CountMyFoodsWithSameIdAsAppFoods"); return(JsonConvert.SerializeObject(e.Message, Formatting.None)); } }