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php – DateTime with microseconds

Posted by: admin April 23, 2020 Leave a comment

Questions:

In my code, I’m using DateTime objects to manipulate dates, then convert them to timestamp in order to save them in some JSON files.

For some reasons, I want to have the same thing as DateTime (or something close), but with microseconds precision (that I would convert to float when inserting inside the JSON files).

My question is : is there a PHP object that is like DateTime, but can handle microseconds too ?

The goal is to be able to manipulate microtimes with objects.

In the date() documentation, there is something that indicates that DateTime can be created with microseconds, but I wasn’t able to find how.

u Microseconds (added in PHP 5.2.2). Note that date() will always
generate 000000 since it takes an integer parameter, whereas
DateTime::format() does support microseconds if DateTime was created
with microseconds.

I have tried to set the timestamp of a DateTime object with a floating value (microtime(true)), but it doesn’t work (I think it converts the timestamp to an int, causing the loss of the microseconds).

Here is how i tried

$dt = new DateTime();
$dt->setTimestamp(3.4); // I replaced 3.4 by microtime(true), this is just to give an example
var_dump($dt);
var_dump($dt->format('u'));

The .4 is not taken into account as you can see here (even though we can use the u format, which corresponds to the microseconds).

object(DateTime)[1]
  public 'date' => string '1970-01-01 01:00:03' (length=19)
  public 'timezone_type' => int 3
  public 'timezone' => string 'Europe/Berlin' (length=13)

string '000000' (length=6)

EDIT : I saw this code, which allows to add microseconds to a DateTime, but I would need to apply a lot of modifications to the microtime before creating the DateTime. Since I will use this a lot, I want to do as little modifications to the microtime as possible before getting the “microtime object”.

$d = new DateTime("15-07-2014 18:30:00.111111");
How to&Answers:

Here’s a very simple method of creating a DateTime object that includes microtime.

I didn’t delve into this question too deeply so if I missed something I apologize but hope you find this helpful.

$date = DateTime::createFromFormat('U.u', microtime(TRUE));
var_dump($date->format('Y-m-d H:i:s.u')); 

I tested it out and tried various other ways to make this work that seemed logical but this was the sole method that worked.
However there was a problem, it was returning the correct time portion but not the correct day portion (because of UTC time most likely)
Here’s what I did (still seems simpler IMHO):

$dateObj = DateTime::createFromFormat('U.u', microtime(TRUE));
$dateObj->setTimeZone(new DateTimeZone('America/Denver'));
var_dump($dateObj->format('Y-m-d H:i:s:u'));

Here’s a working example: http://sandbox.onlinephpfunctions.com/code/66f20107d4adf87c90b5c8c914393d4edef180a2

UPDATE

As pointed out in comments, as of PHP 7.1, the method recommended by Planplan appears to be superior to the one shown above.

So, again for PHP 7.1 and later it may be better to use the below code instead of the above:

$dateObj = DateTime::createFromFormat('0.u00 U', microtime());
$dateObj->setTimeZone(new DateTimeZone('America/Denver'));
var_dump($dateObj->format('Y-m-d H:i:s:u'));

Please be aware that the above works only for PHP versions 7.1 and above. Previous versions of PHP will return 0s in place of the microtime, therefore losing all microtime data.

Here’s an updated sandbox showing both:
http://sandbox.onlinephpfunctions.com/code/a88522835fdad4ae928d023a44b721e392a3295e

NOTE: in testing the above sandbox I did not ever see the microtime(TRUE) failure which Planplan mentioned that he experienced. The updated method does, however, appear to record a higher level of precision as suggested by KristopherWindsor.

Answer:

Looking at a response on the PHP DateTime manual:

DateTime does not support split seconds (microseconds or milliseconds etc.)
I don’t know why this isn’t documented.
The class constructor will accept them without complaint, but they are discarded.
There does not appear to be a way to take a string like “2012-07-08 11:14:15.638276” and store it in an objective form in a complete way.

So you cannot do date math on two strings such as:

<?php
$d1=new DateTime("2012-07-08 11:14:15.638276");
$d2=new DateTime("2012-07-08 11:14:15.889342");
$diff=$d2->diff($d1);
print_r( $diff ) ;

/* returns:

DateInterval Object
(
    [y] => 0
    [m] => 0
    [d] => 0
    [h] => 0
    [i] => 0
    [s] => 0
    [invert] => 0
    [days] => 0
)

*/
?>

You get back 0 when you actually want to get 0.251066 seconds.


However, taking a response from here:

$micro_date = microtime();
$date_array = explode(" ",$micro_date);
$date = date("Y-m-d H:i:s",$date_array[1]);
echo "Date: $date:" . $date_array[0]."<br>";

Recommended and use dateTime() class from referenced:

$t = microtime(true);
$micro = sprintf("%06d",($t - floor($t)) * 1000000);
$d = new DateTime( date('Y-m-d H:i:s.'.$micro, $t) );

print $d->format("Y-m-d H:i:s.u"); //note "u" is microseconds (1 seconds = 1000000 µs).

Reference of dateTime() on php.net: http://php.net/manual/en/datetime.construct.php#

Answer:

/!\ EDIT /!\

I now use https://github.com/briannesbitt/Carbon, the rest of this answer is just here for historical reasons.

END EDIT

I decided to extend the class DateTime using the tips you all gave me.

The constructor takes a float (from microtime) or nothing (in this case it will be initialized with the current “micro-timestamp”).
I also overrided 2 functions that were important : setTimestamp and getTimestamp.

Unfortunately, I couldn’t solve the performances issue, although it’s not as slow as I thought.

Here’s the whole class :

<?php
class MicroDateTime extends DateTime
{
    public $microseconds = 0;

    public function __construct($time = 'now')
    {
        if ($time == 'now')
            $time = microtime(true);

        if (is_float($time + 0)) // "+ 0" implicitly converts $time to a numeric value
        {
            list($ts, $ms) = explode('.', $time);
            parent::__construct(date('Y-m-d H:i:s.', $ts).$ms);
            $this->microseconds = $time - (int)$time;
        }
        else
            throw new Exception('Incorrect value for time "'.print_r($time, true).'"');
    }

    public function setTimestamp($timestamp)
    {
        parent::setTimestamp($timestamp);
        $this->microseconds = $timestamp - (int)$timestamp;
    }

    public function getTimestamp()
    {
        return parent::getTimestamp() + $this->microseconds;
    }
}

Answer:

There are multiple options. But as already provided by Ben, I will try to give you another solution.

If you provided more details on what kind of calculations you want to do it could be changed further.

$time =microtime(true);
$micro_time=sprintf("%06d",($time - floor($time)) * 1000000);
$date=new DateTime( date('Y-m-d H:i:s.'.$micro_time,$time) );
print "Date with microseconds :<br> ".$date->format("Y-m-d H:i:s.u");

or

$time =microtime(true);
var_dump($time);

$micro_time=sprintf("%06d",($time - floor($time)) * 1000000);
$date=new DateTime( date('Y-m-d H:i:s.'.$micro_time,$time) );
print "Date with microseconds :<br> ".$date->format("Y-m-d H:i:s.u");

or

list($ts,$ms) = explode(".",microtime(true));
$dt = new DateTime(date("Y-m-d H:i:s.",$ts).$ms);
echo $dt->format("Y-m-d H:i:s.u");

or

list($usec, $sec) = explode(' ', microtime());
print date('Y-m-d H:i:s', $sec) . $usec;

Answer:

/*
 * More or less standard complete example. Tested.
 */
  private static function utime($format, $utime = null, $timezone = null) {
    if(!$utime) {
      // microtime(true) had too fiew digits of microsecconds
      $time_arr = explode( " ", microtime( false ) );
      $utime = $time_arr[1] . substr( $time_arr[0], 1, 7 );
    }
    if(!$timezone) {
      $timezone = date_default_timezone_get();
    }
    $date_time_zone = timezone_open( $timezone );
    //date_create_from_format( "U.u", $utime ) - had a bug with 3-rd parameter
    $date_time = date_create_from_format( "U.u", $utime );
    date_timezone_set( $date_time, $date_time_zone );
    $timestr = date_format( $date_time, $format );
    return $timestr;
  }

Answer:

This worked for me in PHP 7.2:

$dateTime = \DateTime::createFromFormat('U.u', sprintf('%f', $aFloat), $optionalTimezone);

I got to thinking that since the format code 'u' would output only the microsecond part of a date when converting to a string then doing the reverse would be the same. And that it also expects a period character '.' so if $aFloat happened to be a whole number then default conversion to a string would leave off the decimal point. Initially I thought the float to string conversion needed '%.6f' but the 'u' is expecting a string which is left justified. Trailing zeros are unnecessary.

Answer:

since I resolved my issue i want to share it with You.
Php71+ have microsecconds accuracy, if You want to convert it into nano accuracy just multiply it by 1000 (10^3).

$nsTimestamp = (int) (new \DateTime())->getTimestamp() * 1000

Answer:

$micro_seconds = microtime(false) * 1000000;
echo date('Y-m-d H:i:s.'. floor($micro_seconds));

more about date:
https://www.php.net/manual/en/function.date.php

more about microtime: https://www.php.net/manual/en/function.microtime.php