php. getElementsByTagName. указать родителя элемента.

DOMNodeList Object
(
    [length] => 0
)
DOMNodeList Object
(
    [length] => 0
)

$xpath = new DOMXPath($doc);
$results = $xpath->query("//a[(descendant::var)]");

<?php
//$topic = 3561;
$topic = 301952;
libxml_use_internal_errors(true);
$doc = new DOMDocument;
$doc->loadHtml(file_get_contents("http://rutracker.org/forum/viewtopic.php?t=$topic"));
//определение встроенных объектов
$vars = $doc->getElementsByTagName("var");
//определение внешних объектов
$xpath = new DOMXPath($doc);
$exturls = $xpath->query("//a[(descendant::var)]");
//откуда нумеровать потом файлы
$n = 0;
//
for ($i = 0; $i < $vars->length; $i++) {
	$exturl = $exturls->item($i);
	$class2 = $exturl->attributes->getNamedItem('class')->textContent;
	if (strpos($class2, 'postLink') !== false) {
		$url = $exturl->attributes->getNamedItem('href')->textContent;
		$exthtml = pathinfo($url, PATHINFO_EXTENSION);
		//exturlworking
		$doc2 = new DOMDocument;
		$doc2->loadHtml(file_get_contents($url));
		$xpath2 = new DOMXPath($doc2);
		$exturls2 = $xpath2->query("//a[(descendant::img)]");
		$exturl2 = $exturls2->item($i);
		if (strpos($url, $url) !== false) {
			$img2 = $exturl2->attributes->getNamedItem('href')->textContent;
		}
		$var = $vars->item($i);
		$class = $var->attributes->getNamedItem('class')->textContent;
		if (strpos($class, 'postImg') !== false) {
			$img = $var->attributes->getNamedItem('title')->textContent;
			$ext = pathinfo($img, PATHINFO_EXTENSION);
			//file_put_contents("{$topic}_{$n}.{$ext}", file_get_contents($img2));
			//$n++;
			//file_put_contents("{$topic}_{$n}.{$ext}", file_get_contents($img));
			//$n++;}
			$path = "{$topic}_{$n}.{$ext}";
			$fp = fopen($path, 'w');
			$ch = curl_init(range($img, $img2));
			curl_setopt($ch, CURLOPT_FILE, $fp);
			$data = curl_exec($ch);
			curl_close($ch);
			fclose($fp);
			$n++;
			///////////
			//print_r($img);
		}
	}
}