Find Out All Links In any Website using PHP

FindLinks.php

<?php
function getinboundLinks($domain_name) {
ini_set('user_agent', 'NameOfAgent (<a class="linkclass" href="http://localhost">http://localhost</a>)');
 $url = $domain_name;
$url_without_www=str_replace('http://','',$url);
$url_without_www=str_replace('www.','',$url_without_www);
 $url_without_www= str_replace(strstr($url_without_www,'/'),'',$url_without_www);
$url_without_www=trim($url_without_www);
$input = @file_get_contents($url) or die('Could not access file: $url');
 $regexp = "<a\s[^>]*href=(\"??)([^\" >]*?)\\1[^>]*>(.*)<\/a>";
//$inbound=0;
$outbound=0;
$nonfollow=0;
if(preg_match_all("/$regexp/siU", $input, $matches, PREG_SET_ORDER)) {
foreach($matches as $match) {
# $match[2] = link address
 # $match[3] = link text
//echo $match[3].'<br>';
if(!empty($match[2]) && !empty($match[3])) {
if(strstr(strtolower($match[2]),'URL:') || strstr(strtolower($match[2]),'url:') ) {
$nonfollow +=1;
} else if (strstr(strtolower($match[2]),$url_without_www) || !strstr(strtolower($match[2]),'http://')) {
     $inbound += 1;
    echo '<br>inbound '. $match[2];
 }
else if (!strstr(strtolower($match[2]),$url_without_www) && strstr(strtolower($match[2]),'http://')) {
echo '<br>outbound '. $match[2];
     $outbound += 1;
    }
}
}
}
$links['inbound']=$inbound;
$links['outbound']=$outbound;
$links['nonfollow']=$nonfollow;
return $links;
}
 
// ************************Usage********************************
$Domain='<a class="linkclass" href="http://zachbrowne.com">http://zachbrowne.com</a>';
$links=getinboundLinks($Domain);
echo '<br>Number of inbound Links '.$links['inbound'];
echo '<br>Number of outbound Links '.$links['outbound'];
echo '<br>Number of Nonfollow Links '.$links['nonfollow'];
?>

not working