compare two list and return not matching items using linq

Question

i have a two list

List SentList;
List MsgList;

both have the same property called MsgID;

MsgList            


        

Answer 1

You could do something like:

HashSet sentIDs = new HashSet(SentList.Select(s => s.MsgID));

var results = MsgList.Where(m => !sentIDs.Contains(m.MsgID));

This will return all messages in MsgList which don't have a matching ID in SentList.