Regex help please

I want to control the format of codes users enter to identify cases to three CAPITAL letters followed by 3 numbers eg:


The regex I have in place to do this is:
regex(., ‘[A-Z][A-Z][A-Z][0-9][0-9][0-9]$’)

This nearly works! The problem with it is that it lets me enter as many CAPITAL letter as I like ie it doesn’t give an error if ABCD123 is entered or ABCDE123 is entered.

What am I doing wrong?



Hi Simon,

I think you might just be missing the “match from the beginning” marker, ^. I would try this expression

regex(., '^[A-Z][A-Z][A-Z][0-9][0-9][0-9]$')

or in other words just inserting the ^ at the beginning of your expression. This should make it match from the beginning just like $ makes it match all the way to the end. The default behavior without the beginning/end markers is to match if the pattern is found anywhere in the the string.


Brilliant. Thanks Danny!