Regex for 5 digit number with optional characters

Question

I am trying to create a regex to validate a field where the user can enter a 5 digit number with the option of adding a / followed by 3 letters. I have tried quite a few variations of the following code:

^(\d{5})+?([/]+[A-Z]{1,3})? 

But I just can't seem to get what I want.

For instance l would like the user to either enter a 5 digit number such as 12345 with the option of adding a forward slash followed by any 3 letters such as 12345/WFE.

Answer 1

You probably want:

^\d{5}(?:/[A-Z]{3})?$

You might have to escape that forward slash depending on your regex flavor.

Explanation:

• ^ - start of string anchor
• \d{5} - 5 digits
• (?:/[A-Z]{3}) - non-capturing group consisting of a literal / followed by 3 uppercase letters (depending on your needs you could consider making this a capturing group by removing the ?:).
• ? - 0 or 1 of what precedes (in this case that's the non-capturing group directly above).
• $ - end of string anchor

All in all, the regex looks like this: