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 can do something like

var notSent = MsgSent.Except(MsgList, MsgIdEqualityComparer);

You will need to provide a custom equality comparer as outlined on MSDN

http://msdn.microsoft.com/en-us/library/bb336390.aspx

Simply have that equality comparer base equality only on MsgID property of each respective type. Since the equality comparer compares two instances of the same type, you would need to define an interface or common base type that both Sent and Messages implement that has a MsgID property.