Parse html with regexp

Question

I want to find all <h3> blocks in this example:

<h3>sdf</h3>
sdfsdf
<h3>sdf</h3>
32
<h2>fs</h2>
<h3>23sd</h3>
234
<h1>h1</h1>

(From h3 to other h3 or h2) This regexp find only first h3 block

~\<h3[^>]*\>[^>]+\<\/h3\>.+(?:\<h3|\<h2|\<h1)~is

I use php function preg_match_all (Quote from docs: After the first match is found, the subsequent searches are continued on from end of the last match.)

What i have to modify in my regexp?

ps

<h3>1</h3>
1content
<h3>2</h3>
2content
<h2>h2</h2>
<h3>3</h3>
3content
<h1>h1</h1>

this content have to be parsed as:

[0] => <h3>1</h3>1content
[1] => <h3>2</h3>2content
[2] => <h3>2</h3>3content

Thanks for your answer, but I parse my own page with defined structure. — Andrei Nikolaev
– Andrei Nikolaev, Commented Apr 4, 2014 at 0:47
Please take a look at the DomDocument class. If you parse your HTML, you can easily query all the heading three blocks. — Dave Chen
– Dave Chen, Commented Apr 4, 2014 at 0:58
Questions about parsing HTML with PHP/regex come up so often in SO. Let me echo what has already been said - don't do that. There are many far more able and useful tools for this problem. Look at PHP internal classes DOMDocument and DOMXPath for starters. Make life easier for yourself :) — Darragh Enright
– Darragh Enright, Commented Apr 4, 2014 at 1:09

Casimir et Hippolyte · Accepted Answer · 2014-04-04 13:36:22Z

1

with DOMDocument:

$dom = new DOMDocument();
@$dom->loadHTML($html);

$nodes = $dom->getElementsByTagName('body')->item(0)->childNodes;

$flag = false;
$results = array();

foreach ($nodes as $node) {
    if ( $node->nodeType == XML_ELEMENT_NODE &&
         preg_match('~^h(?:[12]|(3))$~i', $node->nodeName, $m) ):
        if ($flag)
            $results[] = $tmp;
        if (isset($m[1])) {
            $tmp = $dom->saveXML($node);
            $flag = true;
        } else
            $flag = false;

    elseif ($flag):
        $tmp .= $dom->saveXML($node);

    endif;
}

echo htmlspecialchars(print_r($results, true));

with regex:

preg_match_all('~<h3.*?(?=<h[123])~si', $html, $matches);

echo htmlspecialchars(print_r($matches[0], true));

edited Apr 4, 2014 at 13:36

answered Apr 4, 2014 at 2:42

Casimir et Hippolyte

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Comments

Vasili Syrakis · Accepted Answer · 2014-04-04 01:56:26Z

1

You shouldn't use Regex to parse HTML if there is any nesting involved.

Regex

(<(h\d)>.*?<\/\2>)[\r\n]([^\r\n<]+)

Replacement

\1\3
or
$1$3

http://regex101.com/r/uQ3uC2

edited Apr 4, 2014 at 1:56

answered Apr 4, 2014 at 1:38

Vasili Syrakis

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Comments

Minh Nguyen · Accepted Answer · 2014-04-04 01:58:56Z

0

preg_match_all('/<h3>(.*?)<\/h3>/is', $stringHTML, $matches);

answered Apr 4, 2014 at 1:58

Minh Nguyen

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