Regex: Use start of line/end of line signs (^ or $) in different context

Question

While doing some small regex task I came upon this problem. I have a string that is a list of tags that looks e.g like this:
foo,bar,qux,garp,wobble,thud

Answer 1

Just use look-arounds to solve this:

(?<=^|,)garp(?=$|,)

The difference with look-arounds and just regular groups are that with regular groups the comma would be part of the match, and with look-arounds it wouldn't. In this case it doesn't make a difference though.

Answer 2

You can't use ^ and $ in character classes in the way you wish - they will be interpreted literally, but you can use an alternation to achieve the same effect:

(^|,)garp(,|$)

Answer 3

you just need to use word boundary (\b) instead of ^ and $:

\bgarp\b