Form validation url-check

[eluser]manilodisan[/eluser]
We use this one

Code:

function valid_url($str)
{
    return ( ! preg_match('/^(http|https|ftp):\/\/([A-Z0-9][A-Z0-9_-]*(?:\.[A-Z0-9][A-Z0-9_-]*)+):?(\d+)?\/?/i', $str)) ? FALSE : TRUE;
}