Question

I am trying to Compare two lists and keep on each list only items that are unique to each list. Could you assist?

I know how to do intersection, but I actually need to do the opposite

        //Example
        List<String> baseListCopy = new List<String>();
        baseListCopy.Add("Test1");
        baseListCopy.Add("Test2");
        baseListCopy.Add("Test3");
        baseListCopy.Add("Test4");
        baseListCopy.Add("Test5");
        baseListCopy.Add("Test6");
        baseListCopy.Add("Test7");
        baseListCopy.Add("Test8");
        baseListCopy.Add("Test9");

        List<String> resultListCopy = new List<String>();
        resultListCopy.Add("Test1");
        resultListCopy.Add("Test2");
        resultListCopy.Add("Test3");
        resultListCopy.Add("Test40");
        resultListCopy.Add("Test90");

        //returns only items that are present on both lists
        resultListCopy = baseListCopy.Intersect(resultListCopy, StringComparer.InvariantCultureIgnoreCase).ToList();

        //How do I return only items that are unique to that list?

Answer 1

To get all results that are not contained in resultListCopy:

resultListCopy = baseListCopy.Except(resultListCopy, StringComparer.InvariantCultureIgnoreCase)
                             .ToList();