PHP DOMXPath - Can't target the right node - php

Question

I know this is probably covered in other threads, but I've been searching all over StackOverflow and tried many solutions, this is why I'm asking.
With this html:
<div class="someclass">
<table>
<tbody>
<tr>
<th class="state">Status</th>
<th class="name">Name</th>
<th class="type">Type</th>
<th class="length">Length</th>
<th class="height">Height</th>
</tr>
<tr>
<td class="state state2"></td>
<td class="name"></td>
<td class="type t18"></td>
<td class="length">2000 m</td>
<td class="height"></td>
</tr>
<tr>
<td class="state state1"></td>
<td class="name"></td>
<td class="type t18"></td>
<td class="length">2250 m</td>
<td class="height"></td>
</tr>
<tr>
<td class="state state1"></td>
<td class="name"></td>
<td class="type t18"></td>
<td class="length">3000 m</td>
<td class="height"></td>
</tr>
<tr>
<td class="state state2"></td>
<td class="name"></td>
<td class="type t18"></td>
<td class="length">2250 m</td>
<td class="height"></td>
</tr>
</tbody>
</table>
</div>
Now, this is the PHP code I have so far :
$dom = new DOMDocument();
$dom->loadHtmlFile('http://www.whatever.com');
$dom->preserveWhiteSpace = false;
$xp = new DOMXPath($dom);
$col = $xp->query('//td[contains(#class, "state1") and (contains(#class, "state"))]');
$length = 0;
foreach( $col as $n ) {
$parent = $n->parentNode;
$length += $parent->childNodes->item(3)->nodeValue;
}
echo 'Length: ' . $length;
I need to:
1.- Sum the 'length' values so I can echo them, getting rid of the ' m' substring of the given values.
2.- Understand why I'm getting wrong the 'parentNodes', 'childNodes' and 'item()' parts. With many tries I've gotten 'Length: 0'
I know this isn't the place to get a full detailed explanation, but it is really hard to find tutorials targetting these concrete issues. It would be great if someone could give some advice on where I can get this information.
Thanks very much in advance.
Edited the 'Concat' part for simplicity.

Answer 1

Navigation through DOMDocument for a specified childNode value by using DOMXpath
function getInt($string)
{
preg_match("/[0-9]+/i", $string, $val);
$out = 0;
if (isset($val) && !empty($val))
{
$out = $val[0];
}
return intval($out);
}
$dom = new DOMDocument();
$dom->loadHtml($html);
$dom->preserveWhiteSpace = false;
$xp = new DOMXPath($dom);
$length = 0;
foreach($xp->query('//td[#class="state state1"]/following-sibling::*[3]') as $element)
{
$value = $element->nodeValue;
$length += getInt($value);
}
echo $length;