Detailed preg_match_all - php

Question

I am having an issue getting a detailed preg_match_all to work. I keep getting a blank Array.
Here is my code:
<?php
$remote_search = file_get_contents('http://wiki.seg.org/index.php?title=Special%3ASearch&search=drilling&button=');
preg_match_all('%<li><div class=\'mw-search-result-heading\'>(.*) </div> <div class=\'searchresult\'>(.*)</div>
<div class=\'mw-search-result-data\'>(.*)</div></li>%si', $remote_search, $links);
echo '<ul class=\'mw-search-results\'>';
for($i = 0; $i < count($links[1]); $i++) {
echo '<li><div class=\'mw-search-result-heading\'><a href="' . $links[5][$i] . '" title="' . $links[4][$i] . '">' . $links[3][$i] . '<\/a> </div> <div class=\'searchresult\'>' . $links[2][$i] . '<\/div><div class=\'mw-search-result-data\'>' . $links[1][$i] . '<\/div><\/li>';
}
echo '</ul>';
?>
I am trying to grab the link details from code shown below:
<li><div class='mw-search-result-heading'>Dictionary:Cable drilling </div> <div class='searchresult'>{{lowercase}}{{#category_index:C|cable <span class='searchmatch'>drilling</span>}}
</div>
<div class='mw-search-result-data'>132 B (22 words) - 19:58, 20 December 2011</div></li>
When I perform a var_dump($links); I get Array as the result.
The code below works to grab the contents in the section I am trying to pull the variables.
<?php
$remote_search = file_get_contents('http://wiki.seg.org/index.php?title=Special%3ASearch&search=drilling&button=');
preg_match_all('%<ul class=\'mw-search-results\'>(.*)</ul>%si', $remote_search, $links);
$bar = $links[0];
echo '<ul class=\'mw-search-results\'>';
echo $bar;
echo '</ul>';
var_dump($links);
?>
The echo $bar; results in Array and no ouput.
The var_dump($links); in this snippet outputs the content of the ul.
Does anyone see the error in my top snippet that is preventing me from parsing the code the way I am intending it?

Answer 1

Try:
preg_match_all('#<li><div\s*class=\'mw-search-result-heading\'><a\s*href=.([^"]*).\s*title=.([^"]*).>([^<]*)<\/a>\s*<\/div>\s*<div\s*class=\'searchresult\'>(.*?)<\/div>\s*<div\s*class=.mw-search-result-data.>([^<]*)<\/div><\/li>#sim', $remote_search, $links);
print_r($links);
The logic error in your code was the way you were matching <div class=\'searchresult\'>(.*)</div> against <div class='searchresult'>{{lowercase}}{{#category_index:C|cable <span class='searchmatch'>drilling</span>}}</div>
This doesn't work well with regular expressions since there is a nested tag -- the span. So I changed your matching logic to non-greedy: .*?. Also notice how I changed the flag modifiers for the regular expression to sim. I always use these three modifiers whenever I toss a regular expression against HTML. I use them so often I even found a way to arrange the modifier letters into a word namely "sim" as a memory aid to help remember the modifiers.
Happy coding!

Answer 2

Never try to parse html with Regex. Use DOMDocument instead. In your case to get links from file you can do something like:
$dom = new DOMDocument();
$dom->load($url);
$elements = $dom->getElementsByTagName('a');
$links = array();
foreach ($elements as $element)
$links[] = $element->getAttribute('href');
var_dump($links);