Positive Lookbehind Regex

Question

Let's say I have the follow String:

"TEST="test123; xyz=testtest"|PATH="testCookie=1234;"|COOKIE="testCookie2=4321; testCookie=1234;"

I need to write a Regex to only select the testCookie=1234; in the COOKIE="" Field. I tried it with positive lookbehind (?<=COOKIE=") but the problem is my target isn't always on the first position after the (?<=COOKIE=")

Can anyone help me with this regex?

Answer 1

As the value is between the double quotes after COOKIE=" and you tagged pcre:

\bCOOKIE="[^"]*\K\btestCookie=[^;"]*;

Explanation

• \bCOOKIE=" Match the word COOKIE followed by =
• [^"]* Match optional chars other than "
• \K Forget what is matched so far
• \btestCookie= Match the word testCookie followed by =
• [^;"]* Match optional chars other than ; and "
• ; Match literally

See a regex101 demo.

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To get separate matches after COOKIE="

(?:\bCOOKIE="|\G(?!^))[^"]*?\KtestCookie\d+=[^"=;]*[;"]

Explanation

• (?: Non capture group
  • \bCOOKIE=" Match COOKIE=
  • | Or
  • \G(?!^) Assert the current position at the end of the previous match, not at the start of the string
• ) Close the non capture group
• [^"]*? Optionally match as few as possible chars except "
• \K Reset the starting point of the reported match (clear the match buffer)
• testCookie\d+= Match testCookie 1+ digits and =
• [^"=;]*[;"] Optionally match any char except " = ; and then match ; or "

See another regex demo.