Subtract milliseconds from ISO 8601 date string in PHP

Question

I'm having a devil of a time working with what I think (?) are ISO 8601 date strings. I need to be able to subtract milliseconds from them, so that I can do something like this:

$a = '2019-06-09T12:56:52.081Z';

$b = subtract_milliseconds($a, 1);

echo $b; // '2019-06-09T12:56:52.080Z';

Any help would be greatly appreciated, thanks!

Answer 1

Something like this:

$d = new DateTime('2019-06-09T12:56:52.081Z');
$d->setTime($d->format('H'), $d->format('i'), $d->format('s'), $d->format('u') - 1000);
echo $d->format('Y-m-d\TH:i:s.u\Z');
// 2019-06-09T12:56:52.080000Z

Note that this only works since PHP 7.1, solutions for older PHP versions would probably be a lot more manual.