Question

I’m trying to match a SEDOL (exactly 7 chars: 6 alpha-numeric chars followed by 1 numeric char)

My regex

([A-Z0-9]{6})[0-9]{1}

matches correctly but strings greater than 7 chars that begin with a valid match also match (if you see what I mean :)). For example:

B3KMJP4

matches correctly but so does:

B3KMJP4x

which shouldn’t match.

Can anyone show me how to avoid this?

Answer 1

Dollar sign at the end of the regex (called an anchor) signifies end of string:

^([A-Z0-9]{6})\d$

I also added “^” at the start which signifies start of string and prevents matching xB3KMJP4
I also simplified the original regex.

By the way, as per Wikipedia, for the first character, vowels are not used. I’m not quite sure if that’s a rule or a convention.