How to block words?

[manavworld]

How to block some words at register page? I dont want sm user register with any site name, example: google.com, how i can block these words at registration page? I want code for indifun script

[Ponick]

If($sitename=$uid)
{
echo"bla bla bla"
}

[ksg91]

you may look at reg name if it pattern matches url. maybe by doing check for dot in un

[morency]

///function
    function check($string){
    $words = array(
                    //    'banned words/links blaaaa',
                        'google.ro',
                        'yahoo.ro'
                    );


        foreach ($words as $word) {
            if (strstr($string, $word)) {
                return true;
            }
        }
        return false;

    }

////////USAGE :

$string='bla googdro 2';

    if(check($string)){

    echo"you cant use such words ";

    }
    else {
    echo"ok?!";} 

[manavworld]

Thanks 4 help frnds