Wordpress Change Default Display Name Publicy As for all existing users

Question

does anyone know of way I can change the existing display name publicly as for all users. I want to have firstname lastname as the default because this will reflect in the forum

Answer 1

'all'));

    foreach($users as $user){   
        $user = get_userdata($user->ID);    

        $display_name = $user->first_name . " " . $user->last_name;

        if($display_name!=' ') wp_update_user( array ('ID' => $user->ID, 'display_name' => $display_name) );
            else wp_update_user( array ('ID' => $user->ID, 'display_name' => $user->display_login) );

        if($user->display_name == '') 
            wp_update_user( array ('ID' => $user->ID, 'display_name' => $user->display_login) );
    }   
}

?>