regex to match string but not substring

Question

I have this regex /\\$([^:\\n]+)/ and the following strings

1. gid$gid::
2. $gid::
3. ::$gid
4. bar$:$gid:f$oo

currently running the regex on each string independently , I get these matches

1. gid
2. gid
3. gid
4. [ gid , oo ]

I need to alter the regex so there are no matches in number 1 and only one match in number 4 - the middle $gid . In other words, it only matches strings starting with $ that start at the beginning of the string or immediately after a colon .

Thank you in advance!

Answer 1

You may find other examples that further restrict what you need, but this seems to work as you describe:

(^|:)(\$[^:\n]+)

Working here https://regex101.com/r/HGtNw1/1

Answer 2

I ended up using (php)

preg_match_all('/(^|:)\$(\w+)/m', $subject, $matches);

the m options and the implied g options (by _all in the function) were key to getting the answer I needed.

https://www.phpliveregex.com/p/v35