BuddyPress.org

If using bp_core_get_username, make sure you do the following:

– echo the result. Unlike bp_displayed_user_username(), it does not echo automatically. Ie

<?php echo bp_core_get_username( $user_id ); ?>

– Feed it $user_id as an argument. If you don’t, the argument will return false.

See bp-core.php, around line 1005, for the definition of the function, as Brajesh suggested.