匹配html格式的正则！

<?php<br />
<br />
$str = 'afdasdfdsa<ul id="ul1"><br />
  <li>1</li><br />
  <li>2</li><br />
</ul>asdfasdfasd<ul id="ul2"><br />
  <li>3</li><br />
  <li>4</li><br />
</ul>fdsgsdfg';<br />
<br />
preg_match_all('/<ul[^>]*>.*<\/ul>/isU', $str, $matches);<br />
print_r($matches[0]);<br />
<br />
?>

<?php  <br />
$str = '<ul id="ul1"><br />
  <li>1</li><br />
  <li>2</li><br />
</ul><br />
<ul id="ul1"><br />
  <li>3</li><br />
</ul><br />
<ul id="ul1"><br />
  <li>4</li><br />
  <li>5</li><br />
  <li>6</li><br />
</ul>';<br />
preg_match_all('/<ul.*?>.*?<\/ul>/s', $str, $matches);<br />
var_dump($matches);