PHP - function - get image name from wp attachment url

function wp_url_tokenize_sc($string){
    $break = "0";
    $toReturn = "";
    $token = strtok($string, "/");
    while ($token !== false)
    {
        $toReturn = $token;
        $token = strtok("/");
    }
    $token = strtok($toReturn, ".");
    while ($token !== false && $break=="0")
    {
        $toReturn = $token;
        $break = "1";
    }
    return $toReturn;
}