PHP validation/regex for URL

Question

I\'ve been looking for a simple regex for URLs, does anybody have one handy that works well? I didn\'t find one with the zend framework validation classes and have seen sev

Answer 1

Edit:
As incidence pointed out this code has been DEPRECATED with the release of PHP 5.3.0 (2009-06-30) and should be used accordingly.

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Just my two cents but I've developed this function and have been using it for a while with success. It's well documented and separated so you can easily change it.

// Checks if string is a URL
// @param string $url
// @return bool
function isURL($url = NULL) {
    if($url==NULL) return false;

    $protocol = '(http://|https://)';
    $allowed = '([a-z0-9]([-a-z0-9]*[a-z0-9]+)?)';

    $regex = "^". $protocol . // must include the protocol
             '(' . $allowed . '{1,63}\.)+'. // 1 or several sub domains with a max of 63 chars
             '[a-z]' . '{2,6}'; // followed by a TLD
    if(eregi($regex, $url)==true) return true;
    else return false;
}