Intersect can be used to find matches between two collections like so Assign two arrays int array1 1 2 3 int array2 2 3 4 Call Intersect extension method var intersect array1 Intersect array2 Write intersection to screen foreach int value in intersect Console WriteLine value Output 2 3 However what I d like to achieve is the opposite I d like to list items from one collection that are missing from the other Assign two arrays int array1 1 2 3 int array2 2 3 4 Call NonIntersect extension method var intersect array1 NonIntersect array2 I ve made up the NonIntersect method Write intersection to screen foreach int value in intersect Console WriteLine value Output 4

The opposite of Intersect()

As stated, if you want to get 4 as the result, you can do like this:

var nonintersect = array2.Except(array1);

If you want the real non-intersection (also both 1 and 4), then this should do the trick:

var nonintersect = array1.Except(array2).Union( array2.Except(array1));

This will not be the most performant solution, but for small lists it should work just fine.

~ Answered on 2011-04-11 10:56:20