Hello.
Those “random characters” are string patterns. As explained above, () (parentheses) indicate that we want to save whatever is in them into a variable.
Some of the patterns that I used in my previous post:
-
^matches everything at the beginning of string,$matches everything at the end of string, and^...$matches the whole string. -
%wmatches all alphanumeric characters (letters and numbers). I know that usernames can also have underscores, but you can add them yourself with sets[]:[%w_]+. This will match both alphanumeric characters and underscores. -
%smatches all whitespaces. -
+matches 1 or more of the specified character class (in our case%w). -
-matches as few of the specified character classes as possible (in our case%s, we don’t need to match any whitespaces between the arguments).
I recommend reading this article to get to know string patterns better, as they are very interesting and useful. You can also find a list of all magic characters and patterns there.