Online PHP editor | output for k65rY

<?php $array1 = [ (object) ['id' => '204', 'day_id' => '12'], (object) ['id' => '205', 'day_id' => '13'], (object) ['id' => '206', 'day_id' => '14'], (object) ['id' => '207', 'day_id' => '15'], ]; $array2 = [ (object) ['id' => '203', 'day_id' => '11'], (object) ['id' => '205', 'day_id' => '13'], (object) ['id' => '207', 'day_id' => '14'], (object) ['id' => '209', 'day_id' => '17'], ]; var_export( array_udiff( $array1, $array2, fn($a, $b) => $a->id <=> $b->id ) );