Regex question for hyphen match

Oh, I finally understand what you’re doing. Use this regex instead.

String.split("co-operation tree_five one two 1 2 azerty : double:side", ~r/[^a-zA-Z0-9\-]+/u, trim: true)
#=> ["co-operation", "tree", "five", "one", "two", "1", "2", "azerty", "double",
 "side"]

\W-[_] doesn’t mean subtract the underscore from the \W character class. There is no such supported operation in a regex like that which I’m aware of.

I’m not sure what you mean by “substracting the underscore”.

When I simply use ~r/[\W_]/ as the splitter, I get the same result as you with your more complicated regex. It seems as if it were already splitting on -. this way.

If I understand your problem, I think you need to escape - in your character class. The reason is that - is used to defined ranges of characters. For example, ~r/[a-z]/ means all characters from a to z, not a, -, and z. You can escape characters in a character class, by using \. So, for the previous example, to get it to mean a, -, and z, you’d do ~r/[a\-z]/.

Hope that helps