- var_dump: documentation ( source)
- date_create: documentation ( source)
- str_contains: documentation ( source)
<?php
$datetime_before = date_create('now');
$datetime_before->setTime(1,1,1,1);
$datetime_after = clone($datetime_before);
$datetime_after->modify('-100 ms');
$string = $datetime_after->format('Y-m-d H:i:s.u');
if (str_contains($string, "-999")) {
echo 'before: ';
var_dump($datetime_before);
echo PHP_EOL;
echo 'after: ';
var_dump($datetime_after);
echo PHP_EOL;
exit;
}