Shortcode to show a user's display name

Hi,

I’m in need of some help!

I’m trying to create a simple shortcode that will show a user’s display name based on the user ID you insert (or default to the currently logged in user if no ID is provided). Below is a similar shortcode I’ve created to do this for a user’s avatar:

<?php

function avatar_shortcode( $atts ) {

global $current_user;
$user_id = ( is_user_logged_in() ? $current_user->ID : NULL );

extract( shortcode_atts( array(
‘id’ => $user_id,
), $atts ) );

return get_avatar( $id );
}

add_shortcode(‘avatar’, ‘avatar_shortcode’);

?>

[avatar] displays the currently logged in user’s avatar and [avatar id=”1″] display’s the avatar for the user with an ID of 1 and so on. This is exactly what I am looking for to show a user’s display name. Something where [display-name] will show the currently logged in user’s display name and [display-name id=”1″] will show the display name for the user with an ID of 1 and so on.

Please any help will be greatly appreciated!

Thanks,
Jon