Regex with 3 characters or empty

Question

I am trying to write a regular expression that will require 3 characters or empty.

I start with ^[A-Z]{3}$ but I have no idea how to end it.

score 2 · Answer 1 · answered Jun 02 '22 at 13:13

2

You may use an alternation here:

^(?:[A-Z]{3}|)$

This pattern says to match:

^             from the start of the input
(?:
    [A-Z]{3}  3 uppercase letters
    |         OR
              (empty)
)$            end of the input

answered Jun 02 '22 at 13:13

Tim Biegeleisen

Thank It works. What is the meaning of "?:" ? – Laurent Delobelle Jun 02 '22 at 13:22
If this answer resolved your problem, then please consider _accepting_ it, by clicking the green checkmark to the left. – Tim Biegeleisen Jun 02 '22 at 13:23

1 Answers1