Regular Expression: brackets inside Square brackets

Question

I would like to match the following string:

[-ed, -ing, -ment <i>n.</i>]

But exclude:

[-ed, -ing, -ment <b>n.</b>]

And my regex is:

   \[[\-,\s\.(<i>)(</i>)a-z]+\]

Which won't work.

I add brackets to  so it appears as a whole, so  wont be matched.

However, brackets inside square brackets don't seem to work.

How do you think that regex works? Escaping the square brackets means they'll match literal square brackets, so how is `\-,()()a-z` supposed to match `-ed, -ing, -ment n.`?! — Biffen, Feb 11 '15 at 11:14
I noticed that problem you mentioned and rectified it. But `\[[\-,()()a-z]+\]` wont work either. — James King, Feb 11 '15 at 11:17
(After an edit.) Now you're just misunderstanding character classes (`[...]`). `[\-,()()a-z]` is equivalent to `[<>,\/()aiz-]`. May I suggest you read a regex tutorial? — Biffen, Feb 11 '15 at 11:18
Are you sure? `a-z` means any alphabet from a to z, that is `a, b, c, d...z` — James King, Feb 11 '15 at 11:23
Ooops, my bad. It should be `[<>,\/()a-z-]`. It matches `` because `<`, `b` and `>` are all in there. ‘*I add brackets to `` so it appears as a whole*‘, that's where you're wrong; you've simply added `<`, `>`, `/`, `(`, `)` and `i` to the class, most of them twice. — Biffen, Feb 11 '15 at 11:24
Yes, your right. my question is how to match someting as a whole inside a square bracet, if `()` is not the solution. — James King, Feb 11 '15 at 11:34

score 2 · Accepted Answer · answered Feb 11 '15 at 11:41

The following works with the sample string:

\[([^<>]|<i>.*?<\/i>)+?\]

I.e. square brackets containing a number of things that are either a single character that is neither < nor >, or [...] with some content.

It will match the first string and not the second. The problem description however is quite vague, so the regex might need some tweaking. E.g:

Is it just  or anything but ?
Can the square brackets contain nested square brackets?
Are the contents of the square brackets in fact comma-separated elements that must all begin with a hyphen?

1 Answers1