Find Domain From a URL String

Function will take a string and find the domain name of that string.

function stringDomain($string){
    $a = explode('/',$string);
    return str_replace('www.','',$a[2]);
}
$URL = 'http://codefeel.blogspot.ru/p/site-map.html';
echo stringDomain($URL);  // prints: codefeel.blogspot.ru