DateTime with microseconds

/!\ 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;
    }
}

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 for PHP versions prior to 7.1.

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.

NOTE2: Please be aware that there may be rare cases where either approach will fail because of an underlying decision made regarding the handling of microseconds in PHP DateTime code. Either:

  • avoid use of this for scientific purposes or anything where a very high level of accuracy is required.
  • OR be prepared for no microsecond data to return on an exact second mark... (where a microsecond ... which is 1 millionth of a second, will have no data to return as it is complete zeros... from what I've read this is not clear from what's returned and could be done in a better way but is worth creating code to handle ... again, for high precisions uses)

Thanks for the headsup Sz. (see comments).


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;

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#

Tags:

Datetime

Php

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