How to use preg_match to extract data?

Question

I am pretty new to the use of preg_match. Searched a lot for an answer before posting this question. Found a lot of posts to get data based on youtube ID etc. But nothing as

Answer 1

You can try this:

preg_match('~(?<=\[#)\d+(?=])~', $txt, $match);

(?<=..) is a lookbehind (only a check)

(?=..) is a lookahead