PHP Domain name handler function

The following one is to determine whether the domain name entered is legal, and then the http,https,ftp for processing, analysis and send

function _scan_url ()
{
$req = $this->_url;

$pos = Strpos ($req, '://');
$this->_protocol = Strtolower (substr ($req, 0, $pos));

$req = substr ($req, $pos +3);
$pos = Strpos ($req, '/');
if ($pos = = False)
$pos = strlen ($req);
$host = substr ($req, 0, $pos);

if (Strpos ($host, ': ')!== false)
{
List ($this->_host, $this->_port) = Explode (': ', $host);
}
Else
{
$this->_host = $host;
$this->_port = ($this->_protocol = = ' https ')? 443:80;
}

$this->_uri = substr ($req, $pos);
if ($this->_uri = = ")
$this->_uri = '/';
}

Function Cleandomain ($q, $w =0) {//collating domain name $w = 1 filtering www. prefix $w =0 not filtered
  $q = Htmlspecialchars (Strtolower (Trim ($q));
 if (substr ($q, 0,7) = = "http://" | | substr ($Q, 0,8) = = "https://" | | substr ($Q, 0,6) = = "ftp://") {
   $q = Str_replace ("http:/", "", $q);
   $q = Str_replace ("https:/", "", $q);
   $q = Str_replace ("ftp:/", "", $q);
 }
 if substr ($q, 0,4) = = "www." && $w ==1) {
   $q = Str_replace ("www.", "", $q);
 }< br>   $q = Trim ($q, "/");
 return $q;
}