Question

I need a regex that extract text inside a delimiter but I’m
having problem extracting the value inside the delimiter [DATA n] and [END DATA]

Here’s my regex

(?<=\[DATA\s+\d+\]).*(?=\[END DATA\])

Here’s example data I want to match

Some text here

[DATA 1]
data one 
some more data
[END DATA]
[DATA 2]
data two
more data
data
[END DATA]
[DATA n]
more data 
data 
[END DATA]

Answer 1

You appear to be using regular expressions features like lookbehind and lookahead when you don’t really need them. Try:

\[DATA\s+\d+\](.*?)\[END DATA\]

There’s only one capture group in this regular expression, (.*?). After using this, the result you’re looking for should be in capture group 1.

Note also that I’ve used the non-greedy .*? match that will match up until the first following instance of [END DATA]. Without this, if you use just .*, you’ll capture everything up to the last [END DATA].