If you are using Affiliates by @itthinx and you need to display the referrer username, now you can use this shortcode:
add_shortcode( 'affiliates_username', 'affiliates_username_shortcode' );
function affiliates_username_shortcode( $atts ) {
if ( !class_exists( "Affiliates_Service" ) ) {
include_once( AFFILIATES_CORE_LIB . '/class-affiliates-service.php' );
}
$output = "";
$affiliate_id = Affiliates_Service::get_referrer_id();
if ( $affiliate_id ) {
if ( $affiliate_id !== affiliates_get_direct_id() ) {
if ( $user_id = affiliates_get_affiliate_user( $affiliate_id ) ) {
if ( $user = get_user_by( 'id', $user_id ) ) {
$output .= $user->user_login;
}
}
}
}
return $output;
}