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How should I format a regex for a positive lookbehind in ColdFusion?

I have a string that contains a path, like "this/is/a/path/to/the/root/subfolder". I'm attempting to get everything after "root" (in this case "/subfolder".)

According to the documentation at regular-expressions.info, (?<=s)t should match the first "t" in "streets". I used that to make this:

<cfset regex = "(?<=root).*">
#REFind(regex, myString)#

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This gives me the error "Reason: Sequence (?<...) not recognized."

I've Googled up a storm and tried escaping characters, changing the parentheses... but the most common error that throws is "?+* follows nothing in expression" with the occasional "Malformed regular expression" "?<="".

I'm at a loss. Can you help? Thanks!

Coast Line

try using like this

<cfset filepath = "this/is/a/path/to/the/root/subfolder">

<cfset fileName = ListLast(filePath, "/")>

SOLUTION

kaufmed

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_agx_

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SiobhanElara

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Thank you kaufmed and _agx_! I didn't know that about CF and the lookbehind.

(myselfrandhawa, I might also have something like this/is/a/path/to/the/root/subfolder/and/another, so I can't use ListLast. But thank you for the suggestion!)