如何将CURL与简单的HTML DOM结合起来

I'm attempting to send a CURL request and then use 'simple_html_dom' class to find the html elements I want. (Parsing) — in this case I send a CURL request to 'google.com' and then use 'simple_html_dom' class to select all of the links of the page. (or any other HTML tags.)

The problem:
I don't know how to combine CURL with the 'simple_html_dom' class.

Here is my code:

Curl Request:

function GetPage($url){ 
      $curl = curl_init();
      curl_setopt($curl, CURLOPT_URL, $url);
      curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
      curl_setopt($curl, CURLOPT_HEADER, true);
      $userAgent = 'Googlebot/2.1 (http://www.googlebot.com/bot.html)';
      curl_setopt($curl, CURLOPT_USERAGENT, $userAgent);
      $str = curl_exec($curl);
      curl_close($curl);

        return $str;
    }
        $output = GetPage('http://www.google.com/');

How I attempt to use 'simple_html_dom' class:

        $html = new simple_html_dom();
        $html->load($output, true, false);
        $links = $html->find('a');          
        foreach ($links as $link){
            echo $link.'</br>';
        }

When I load my file, it shows no errors, but it doesn't show the links I selected either.

Note:
I've looked through this website to make sure this question hasn't been answered,but it actually was answered a couple of times, but it still didn't solve it.