PHP DateTime microseconds always returns 0

Question

this code always returns 0 in PHP 5.2.5 for microseconds:

format(\"Y-m-d\\TH:i:s.u\") . \"\\n\";
?>


        

Answer 1

This should be the most flexible and precise:

function udate($format, $timestamp=null) {
    if (!isset($timestamp)) $timestamp = microtime();
    // microtime(true)
    if (count($t = explode(" ", $timestamp)) == 1) {
        list($timestamp, $usec) = explode(".", $timestamp);
        $usec = "." . $usec;
    }
    // microtime (much more precise)
    else {
        $usec = $t[0];
        $timestamp = $t[1];
    }
    // 7 decimal places for "u" is maximum
    $date = new DateTime(date('Y-m-d H:i:s' . substr(sprintf('%.7f', $usec), 1), $timestamp));
    return $date->format($format);
}
echo udate("Y-m-d\TH:i:s.u") . "\n";
echo udate("Y-m-d\TH:i:s.u", microtime(true)) . "\n";
echo udate("Y-m-d\TH:i:s.u", microtime()) . "\n";
/* returns:
2015-02-14T14:10:30.472647
2015-02-14T14:10:30.472700
2015-02-14T14:10:30.472749
*/

Answer 2

Some answers make use of several timestamps, which is conceptually wrong, and overlapping issues may occur: seconds from 21:15:05.999 combined by microseconds from 21:15:06.000 give 21:15:05.000.

Apparently the simplest is to use DateTime::createFromFormat() with U.u, but as stated in a comment, it fails if there are no microseconds.

So, I'm suggesting this code:

function udate($format, $time = null) {

    if (!$time) {
        $time = microtime(true);
    }

    // Avoid missing dot on full seconds: (string)42 and (string)42.000000 give '42'
    $time = number_format($time, 6, '.', '');

    return DateTime::createFromFormat('U.u', $time)->format($format);
}

Answer 3

date_create

time: String in a format accepted by strtotime(), defaults to "now".

strtotime

time: The string to parse, according to the GNU » Date Input Formats syntax. Before PHP 5.0.0, microseconds weren't allowed in the time, since PHP 5.0.0 they are allowed but ignored.

Answer 4

This function pulled from http://us3.php.net/date

function udate($format, $utimestamp = null)
{
    if (is_null($utimestamp))
        $utimestamp = microtime(true);

    $timestamp = floor($utimestamp);
    $milliseconds = round(($utimestamp - $timestamp) * 1000000);

    return date(preg_replace('`(?<!\\\\)u`', $milliseconds, $format), $timestamp);
}

echo udate('H:i:s.u'); // 19:40:56.78128

Very screwy you have to implement this function to get "u" to work... :\

Answer 5

\DateTime::createFromFormat('U.u', microtime(true));

Will give you (at least on most systems):

object(DateTime)(
  'date' => '2015-03-09 17:27:39.456200',
  'timezone_type' => 3,
  'timezone' => 'Australia/Darwin'
)

But there is a loss of precision because of PHP float rounding. It's not truly microseconds.

Update

This is probably the best compromise of the createFromFormat() options, and provides full precision.

\DateTime::createFromFormat('0.u00 U', microtime());

gettimeofday()

More explicit, and maybe more robust. Solves the bug found by Xavi.

$time = gettimeofday(); 
\DateTime::createFromFormat('U.u', sprintf('%d.%06d', $time['sec'], $time['usec']));

Answer 6

Inside of an application I am writing I have the need to set/display microtime on DateTime objects. It seems the only way to get the DateTime object to recognize microseconds is to initialize it with the time in format of "YYYY-MM-DD HH:MM:SS.uuuuuu". The space in between the date and time portions can also be a "T" as is usual in ISO8601 format.

The following function returns a DateTime object initialized to the local timezone (code can be modified as needed of course to suit individual needs):

// Return DateTime object including microtime for "now"
function dto_now()
{
    list($usec, $sec) = explode(' ', microtime());
    $usec = substr($usec, 2, 6);
    $datetime_now = date('Y-m-d H:i:s\.', $sec).$usec;
    return new DateTime($datetime_now, new DateTimeZone(date_default_timezone_get()));
}