Regex to match a part of a path in C++

Question

I'm having issues trying to come up with a regex in order to match a part of a path and then use the second capture group to extract it

let suppose that we have the following paths:

./var/lib/

var/lib/

./var/lib

from those examples that section of the string that I'm trying to match would be just (var/lib) for all those inputs, so I decided to try using a regex.

This is what I have so far:

(\.\/)?[A-Za-z0-9][A-Za-z0-9\/]+(\/)?$

So far it matches all the possible scenarios but it does not match the last capture group.

so for example ./var/lib/test/ is matched correctly, but the las / is not matched by the third capture group but for the second one and I cannot have that.

the correct behavior should be:

First group	Second Group	Third group
./	var/lib/test	/

Answer 1

You just need to use a lazy quantifier +? instead of greedy + (also, you missed second group in your original regex):

(\.\/)?([A-Za-z0-9][A-Za-z0-9\/]+?)(\/)?$

Lazy quantifier matches as little as possible, but since you require the match to include end of string with $, it has no choice but to capture everything except possibly last /.

See online on regex101
See online on godbolt