php Extract Best guess for this image result from google image search?

You could use preg_match instead.

As you're getting the HTML back from CURL, you can then use Regex to match the text instead:

function fetch_google($terms="sample search",$numpages=1,$user_agent='Mozilla/5.0 (Windows NT 6.1; rv:8.0) Gecko/20100101 Firefox/8.0')  {    $searched="";    for($i=0;$i<=$numpages;$i++)    {        $ch = curl_init();        $url="http://www.google.com/searchbyimage?hl=en&image_url=".urlencode($terms);        curl_setopt ($ch, CURLOPT_URL, $url);        curl_setopt ($ch, CURLOPT_USERAGENT, $user_agent);        curl_setopt ($ch, CURLOPT_HEADER, 0);        curl_setopt ($ch, CURLOPT_FOLLOWLOCATION, 1);        curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1);        curl_setopt ($ch, CURLOPT_REFERER, 'http://www.google.com/');        curl_setopt ($ch,CURLOPT_CONNECTTIMEOUT,120);        curl_setopt ($ch,CURLOPT_TIMEOUT,120);        curl_setopt ($ch,CURLOPT_MAXREDIRS,10);        curl_setopt ($ch,CURLOPT_COOKIEFILE,"cookie.txt");        curl_setopt ($ch,CURLOPT_COOKIEJAR,"cookie.txt");        $searched=$searched.curl_exec ($ch);        curl_close ($ch);    }    $matches = array();    preg_match('/Best guess for this image:[^<]+<a[^>]+>([^<]+)/', $searched, $matches);    return (count($matches) > 1 ? $matches[1] : false);}

If you want to use DOMDocument you can get the values with the following modification.

    <?phpfunction fetch_google($terms="sample search",$numpages=1,$user_agent='Mozilla/5.0 (Windows NT 6.1; rv:8.0) Gecko/20100101 Firefox/8.0')  {    $searched="";    for($i=0;$i<=$numpages;$i++)    {        $ch = curl_init();        $url="http://www.google.com/searchbyimage?hl=en&image_url=".urlencode($terms);        curl_setopt ($ch, CURLOPT_URL, $url);        curl_setopt ($ch, CURLOPT_USERAGENT, $user_agent);        curl_setopt ($ch, CURLOPT_HEADER, 0);        curl_setopt ($ch, CURLOPT_FOLLOWLOCATION, 1);        curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1);        curl_setopt ($ch, CURLOPT_REFERER, 'http://www.google.com/');        curl_setopt ($ch,CURLOPT_CONNECTTIMEOUT,120);        curl_setopt ($ch,CURLOPT_TIMEOUT,120);        curl_setopt ($ch,CURLOPT_MAXREDIRS,10);        curl_setopt ($ch,CURLOPT_COOKIEFILE,"cookie.txt");        curl_setopt ($ch,CURLOPT_COOKIEJAR,"cookie.txt");        $searched=$searched.curl_exec ($ch);        curl_close ($ch);    }    $xml = new DOMDocument();    @$xml->loadHTML($searched);    if(true == ($topblock = $xml->getElementByID('topstuff')))    {        foreach($topblock->getElementsByTagName('div') as $div){            if(strstr(strtolower($div->nodeValue), "guess")){                foreach($div->getElementsByTagName('a') as $a){                    $last = $a->nodeValue;                }            }        }    }    return $last; }$content = fetch_google($_GET['img'],1);echo $content."<br>";?>