What '?' Does in regex?

Question

I have a regular expression : re.search(r"^[+-]?[0-9]*\.[0-9]*

Answer 1

rodwynnejones is right, I corrected my answer.

Answer 2

I'm sure the "?" means zero or one occurrence.

Answer 3

edited
? zero or one occurance only of preceding letter
[+-]? matches + or - or ''

Answer 4

https://www.sololearn.com/learn/10441/?ref=app