Online PHP editor | refs for RG44S

<?php $emails = [ (object) ['email' => 'a'], (object) ['email' => 'b'], (object) ['email' => 'c'] ]; $userEmails = [ (object) ['user_email' => 'c'], (object) ['user_email' => 'a'], (object) ['user_email' => 'd'] ]; var_export( array_udiff( $emails, $userEmails, fn($a, $b) => ($a->email ?? $a->user_email) <=> ($b->email ?? $b->user_email) ) );