I want to validate the string to be an integer of such format of undefined length. /\A (?<d> ( ( (\g<d>[[:space:]])? \d)? \d)? \d) \z/x === "12 123 123" but it throws SyntaxE...

This is very much related to Regular Expression to match outer brackets however, I specifically want to know how or whether it's possible to do this regex's recursive pattern? I'm yet to find a pyt...

PCRE has a feature called recursive pattern, which can be used to match nested subgroups. For example, consider the "grammar" Q -> \w | '[' A ';' Q* ','? Q* ']' | '<' A '>' A -&g...

I seem to remember that Regular Expressions in DotNet have a special mechanism that allows for the correct matching of nested structures, like the grouping in "( (a ( ( c ) b ) ) ( d ) e )". What...

i know there are several questions about regex recursion in .net. I can write somewhat complex regex expressions but this recursion is beyond me, i am just not able to write it. This are the quest...

I would like to match text enclosed in brackets etc in Perl. How can I do that? This is a question from the official perlfaq. We're importing the perlfaq to Stack Overflow.

After reading polygenelubricants's series of articles on advanced regular expressions techniques (particularly How does this Java regex detect palindromes?), I decided to attempt to create my own P...