Modify microseconds of a PHP DateTime object - php

Question

I have a PHP DateTime object with microseconds created as follows:
$time = microtime(true);
$microseconds = sprintf('%06d', ($time - floor($time)) * 1000000);
$dt = new DateTime(date('Y-m-d H:i:s.' . $microseconds, $time));
How can I modify the microseconds value of $dt, without creating a completely new DateTime instance?

Answer 1

You can't.
There are three methods that can modify the value of a DateTime instance: add, sub and modify. We can rule out add and sub immediately because they work in terms of a DateInterval which does not have sub-second precision.
modify accepts a string in one of the standard recognized formats. Of those formats, only the relative ones are of interest here because the other ones work in an absolute manner; and there is no relative format that allows tweaking the msec part (that unit is not recognized).

Answer 2

as of PHP 7.1
DateTime::setTime() supports microseconds.

Answer 3

This seems to have been available since 7.1.0-rc4
$dt = new DateTime('2020-01-01 0:00');
$dt->modify('+500 ms'); // Milliseconds.
$dt->modify('+123456 usec'); // Microseconds.
$dt->modify('+123456 microseconds'); // This works too.
It's mentioned here in the manual.

Answer 4

Manually creating a DateTime object with micro seconds:
$d = new DateTime("15-07-2014 18:30:00.111111");
Getting a DateTime object of the current time with microseconds:
$d = date_format(new DateTime(),'d-m-Y H:i:s').substr((string)microtime(), 1, 8);
Difference between two DateTime objects in microseconds (e.g. returns: 2.218939)
//Returns the difference, in seconds, between two datetime objects including
//the microseconds:
function mdiff($date1, $date2){
$date1sec = strtotime($date1->format('d-m-Y H:i:s.u'));
$date2sec = strtotime($date2->format('d-m-Y H:i:s.u'));
//Absolute val of Date 1 in seconds from (EPOCH Time) - Date 2 in seconds from (EPOCH Time)
$secdiff = abs($date1sec-$date2sec);
//Creates variables for the microseconds of date1 and date2
$micro1 = $date1->format("u");
$micro2 = $date2->format("u");
if (($date1sec<$date2sec && $micro1>$micro2)||($date1sec>$date2sec && $micro1<$micro2)){
$microdiff = abs(1000000 - abs($micro1-$micro2));
$secdiff = $secdiff - 1;
} else {
$microdiff = abs($micro1 - $micro2);
}
//Creates the variable that will hold the seconds (?):
$difference = $secdiff.".".$microdiff;
return $difference;
}
Essentially it finds the difference for the DateTime Objects using strtotime and then adding the extra microseconds on.
Do you need me to create add and sub?

Answer 5

i had a similar problem and ended up having to wrap the whole thing
https://gist.github.com/chandeeland/9817516

Answer 6

For the people only in need to zero-out microseconds (I had to because of database layer) here's the snippet I ended up using:
$format = "Y-m-d H:i:s e";
$now = (new \DateTime())->format($format);
$dateTime = \DateTime::createFromFormat($format, $now);
Note that using $format = 'c', ISO 8601, will not work, as explained here (https://stackoverflow.com/a/10478469/8119317).