It answer the question "how to get a unique set of the values of two arrays". I did not realize he wanted the symmetric difference between two sets (and didn't know what symmetric difference was until I looked it up) and forgot that the heading has changed to How can I remove duplicate elements from a list or array, in 5.8.* at least. I esp. thought point E would be helpful and should point out that perldoc -q 'symmetric difference' will give an example of that too, though I prefer the module now that I see this. I'll leave it there though as it many answer later questions.