How do we create such a regular expression to extract data?

Question

<br>Aggie<br><br>John<br><p>Hello world</p><br>Mary<br><br><b>Peter</b><br>

I'd like to create a regexp that safely matches these:

<br>Aggie<br>
<br>John<br>
<br>Mary<br>
<br><b>Peter</b><br>

This is possible that there are other tags (e.g. ,<strike>...etc ) between each pair of   and they have to be collected just like the  Peter 

How should the regexp look like?

http://www.codinghorror.com/blog/archives/001311.html *sigh* — Joey, Nov 19 '09 at 15:21
I understand it's sometimes better to do this using an HTML parser. But this is actually just a made-up example that I want to see what syntax it would be if it really has to be done in regex. — bobo, Nov 19 '09 at 17:09

score 6 · Answer 1 · answered Nov 19 '09 at 15:22

6

If you learn one thing on SO, let it be - "Do not parse HTML with a regex". Use an HTML Parser

answered Nov 19 '09 at 15:22

RC.

To anyone pointing automatically to this one, quoting from the very same blog post: "Many programs will neither need to, nor should, anticipate the entire universe of HTML when parsing." It's absolutely OK to parse a HTML-like input if you keep this in mind. – candiru Nov 19 '09 at 15:28
2

This question is missing the obligatory bobince reference: http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454 – intgr Nov 19 '09 at 15:29
@candiru: The asker explicitly asked for a regexp that is **"safe"**. Regexps are fine for one-off hacks, but they are certainly not safe. – intgr Nov 19 '09 at 15:30
1

intgr: It's linked from Jeff's post I linked in the comment to the question. It's just another pointer to dereference :-) – Joey Nov 19 '09 at 15:44

score 1 · Accepted Answer · answered Nov 19 '09 at 18:53

1

<br>.*?<br>

will match anything from one   tag to the closest following one.

The main problem with parsing HTML using regexes is that regexes can't handle arbitrarily nested structures. This is not a problem in your example.

answered Nov 19 '09 at 18:53

Tim Pietzcker

Aaron Digulla · Answer 3 · 2009-11-19T15:46:35.527

0

Split the string at ( )+. You'll get empty strings at the beginning and the end of the result, so you need to remove them, too.

If you want to preserve the  , then this is not possible unless you know that there is one before and after each element in the result.

edited Nov 19 '09 at 15:46

answered Nov 19 '09 at 15:24

Aaron Digulla

You can still pre- and append an `
` to each result, though. Not nice but if the OP *requires* the `
` ... – Joey Nov 19 '09 at 16:03

3 Answers3