Is this possible with regular expression?

Question

() [] {} these are valid matches but ({)} is false, eg.:

() - true
()[]- true
()[]{} - ture
([]) - false
(){[}] - false.

Can I use regular expression to compute this?

You asked an almost identical question here http://stackoverflow.com/questions/16113504/java-best-way-to-implement-this-code — peter.murray.rust, Apr 19 '13 at 21:57
What a strangely positioned question, did you hear someone say that regex cannot be used to balance parenthesis? — Esailija, Apr 19 '13 at 21:58
@peter.murray.rust: I don't see a duplication. That was more broad than this question (which is still broad, mind you). — Makoto, Apr 19 '13 at 21:58
possible duplicate of [Can regular expressions be used to match nested patterns?](http://stackoverflow.com/questions/133601/can-regular-expressions-be-used-to-match-nested-patterns) — Makoto, Apr 19 '13 at 21:59
@mellamokb: "Best way" vs. "Is this possible with...". That's what I was looking at. — Makoto, Apr 19 '13 at 21:59
No, you're going to want to look in to `Context-free grammars` and `deterministic pushdown automata` http://en.wikipedia.org/wiki/Context-free_grammar#Well-formed_nested_parentheses_and_square_brackets — Michael, Apr 19 '13 at 22:01

score 5 · Answer 1 · answered Apr 19 '13 at 21:58

5

No, one of known limitations of regular expressions is that it can't tell whether parentheses are well formed.

answered Apr 19 '13 at 21:58

1 Answers1