- print_r: documentation ( source)
- array_diff: documentation ( source)
<?php
$dateArray1 = [new \DateTimeImmutable('Y-m-d 00:00:00')];
$dateArray2 = [new \DateTimeImmutable('Y-m-d 00:00:00')];
$dates = array_diff($dateArray1, $dateArray2);
print_r($dates);