php yardım

<?php
require_once('fonksiyon.php');
if(isset($_POST['link']) || isset($_GET['link'])) {
    if(isset($_POST['link'])) { $url = $_POST['link']; }
    else if(isset($_GET['link'])) { $url = $_GET['link']; }
    $url = "http://www.".trim(eregi_replace('www.','', linkkes($url)));
if(!is_valid_url($url)){
    echo '<div id="sonuclar">Gecerli bir internet adresi yazmalisiniz...</div>';
} else {
    
    $alexa    = alexaRank($url);
    ?>

// Link mi Değil mi ?
function is_valid_url($url = '') { 
    
    // SCHEME
    $urlregex = "^(https?|ftp)\:\/\/";
$URLRegex = '/(?:(?<!(\[\/url\]|\[\/url=))(\s|^))'; // No [url]-tag in front and 
$URLRegex.= '(';                                    // Start capturing URL
$URLRegex.= '(https?|ftps?|ircs?):\/\/';            // Protocol
$URLRegex.= '\S+';                                  // Any non-space character
$URLRegex.= ')';                                    // Stop capturing URL
$URLRegex.= '(?:(?<![[:punct:]])(\s|\.?$))/i';   
$URLRegex = '/(?:(?<!(\[\/link\]|\[\/link=))(\s|^))'; // No [url]-tag in front and is start of string, or has whitespace in front
$URLRegex.= '(';                                    // Start capturing URL
$URLRegex.= '(https?|ftps?|ircs?|http?|ftp?|irc?):\/\/';            // Protocol
$URLRegex.= '\S+';                                  // Any non-space character
$URLRegex.= ')';                                    // Stop capturing URL

    // USER AND PASS (optional)
    $urlregex .= "([a-z0-9+!*(),;?&=\$_.-]+(\:[a-z0-9+!*(),;?&=\$_.-]+)?@)?";

    // HOSTNAME OR IP
    $urlregex .= "[a-z0-9+\$_-]+(\.[a-z0-9+\$_-]+)*";  // http://x = allowed (ex. http://localhost, http://routerlogin)
    $urlregex .= "[a-z0-9+\$_-]+(\.[a-z0-9+\$_-]+)+";  // http://x.x = minimum
    $urlregex .= "([a-z0-9+\$_-]+\.)*[a-z0-9+\$_-]{2,3}";  // http://x.xx(x) = minimum
    //use only one of the above

    // PORT (optional)
    $urlregex .= "(\:[0-9]{2,5})?";
    // PATH  (optional)
    $urlregex .= "(\/([a-z0-9+\$_-]\.?)+)*\/?";
    // GET Query (optional)
    $urlregex .= "(\?[a-z+&\$_.-][a-z0-9;:@/&%=+\$_.-]*)?";
    // ANCHOR (optional)
    $urlregex .= "(#[a-z_.-][a-z0-9+\$_.-]*)?\$";

    if (eregi($urlregex, $url)) { return true; } else { return false; }
}
?>