I'm a marketer and Google assigns clicks a Google Click ID (GCLID) on paid traffic. These come through appended to URLs. Sometimes, I need to isolate the value in a Google Sheet using REGEX.
Here's what I've done to extract the GCLID in Sublime Text but it is not yielding the expected result in google sheets:
(?<=gclid=).*?[?=A-Za-z0-9\-\_]{10,100}
100 case sensitive alphanumeric characters is the max for these Ids. They also consist of "-" as well as "_".
I believe this is an effective use of a REGEX positive lookback that yields just the GCLID at the end of the URL query.
The use of a ? in Google Sheets seems to break the expression.
You may use
=REGEXEXTRACT(A1, "gclid=([\w-]+)")
Note that the REGEXEXTRACT function only returns the captured substring(s) if the capturing group(s) is defined in the regular expression.
The regex matches
gclid= - a literal string([\w-]+) - Capturing group 1: any one or more letters, digits, _ or - (note the - at the end of a character class does not have to be escaped to be parsed as a literal hyphen).