Retrieves the customer's memberships ("active" or "canceled" status) and returns the ID numbers of the associated membership levels.
Parameters:
- $customer_id (int) - ID of the customer to check. Uses currently logged in customers if omitted.
Return values:
array
- Array of membership level IDs.
Examples:
Checks to see if the current customer is on the membership level #2:
<?php if( in_array( 2, rcp_get_customer_membership_level_ids() ) ) : ?> <p>Content inside here would only be visible to active members with a membership level ID of 2.</p> <?php endif; ?>