Question

This works for any strings that have whitespaces in them

str.downcase.tr!(" ", "_")

but strings that dont have whitespaces just get deleted

So “New School” would change into “new_school” but “color” would be “”, nothing!

Answer 1

The docs for tr! say

Translates str in place, using the same rules as String#tr. Returns str, or nil if no changes were made.

I think you’ll get the correct results if you use tr without the exclamation.