@since: BuddyBoss 1.2.8
Description
bp_get_userid_from_mentionname()

Get a user ID from a “mentionname”, the name used for a user in @-mentions.

Source: bp-core/bp-core-functions.php:4650

bp_find_mentions_by_at_sign()

Locate usernames in an content string, as designated by an @ sign.

Source: bp-core/bp-core-functions.php:4613

bp_admin_registration_setting_tutorial()

Link to Registration tutorial

Source: bp-core/admin/bp-core-admin-settings.php:1283