PHP snippets for URLs

url-snippets.php

//Get host name from URL
preg_match('@^(?:https?://)?([^/]+)@i',
    "http://www.php.net/index.html", $matches);
$host = $matches[1];

//Get last two segments of host name
preg_match('/[^.]+\.[^.]+$/', $host, $matches);
echo "domain name is: {$matches[0]}\n";

//Check for valid domain 
private function isValidDomainName($domainInput)
{
    return (preg_match("/^([a-z\d](-*[a-z\d])*)(\.([a-z\d](-*[a-z\d])*))*$/i", $domainInput) //valid chars check
            && preg_match("/^.{1,253}$/", $domainInput) //overall length check
            && preg_match("/^[^\.]{1,63}(\.[^\.]{1,63})*$/", $domainInput)   ); //length of each label
}