(PHP 5 >= 5.2.0, PHP 7)
Representation of date and time.
$format
, string $time
[, DateTimeZone $timezone
] )DateTime::ATOMDATE_ATOMDATE_COOKIEDateTime::ISO8601DATE_ISO8601Note: This format is not compatible with ISO-8601, but is left this way for backward compatibility reasons. Use
DateTime::ATOMorDATE_ATOMfor compatibility with ISO-8601 instead.
DateTime::RFC822DATE_RFC822DateTime::RFC850DATE_RFC850DateTime::RFC1036DATE_RFC1036DateTime::RFC1123DATE_RFC1123DateTime::RFC2822DATE_RFC2822DateTime::RFC3339DATE_RFC3339DATE_ATOM (since PHP 5.1.3)
DateTime::RFC3339_EXTENDEDDATE_RFC3339_EXTENDEDDateTime::RSSDATE_RSSDateTime::W3CDATE_W3C
| 版本 | 说明 |
|---|---|
| 7.0.0 | Added constants: DATE_RFC3339_EXTENDED and DateTime::RFC3339_EXTENDED. |
| 5.5.0 | The class now implements DateTimeInterface. |
| 5.4.24 | The COOKIE constant was changed to reflect RFC 1036 using a four digit year rather than a two digit year (RFC 850) as prior versions. |
| 5.2.2 | DateTime object comparison with the comparison operators changed to work as expected. Previously, all DateTime objects were considered equal (using ==). |
This might be unexpected behavior:
<?php
$date1 = DateTime::createFromFormat('Y-m-d H:i:s', '2017-08-31 00:00:00');
$date1->modify('+1 month');
#or use the interval
#$date1->add(new DateInterval("P1M"));
#will produce 2017-10-1
#not 2017-09-30
if you'd like to print all the built-in formats,
<?php
foreach((new ReflectionClass('DateTime'))->getConstants() as $name=>$format){
echo 'DateTime::'.$name.' -> '.date($format).PHP_EOL;
}
At PHP 7.1 the DateTime constructor incorporates microseconds when constructed from the current time. Make your comparisons carefully, since two DateTime objects constructed one after another are now more likely to have different values.
http://php.net/manual/en/migration71.incompatible.php
Note that the ISO8601 constant will not correctly parse all possible ISO8601 compliant formats, as it does not support fractional seconds. If you need to be strictly compliant to that standard you will have to write your own format.
Bug report #51950 has unfortunately be closed as "not a bug" even though it's a clear violation of the ISO8601 standard.
A good way I did to work with millisecond is transforming the time in milliseconds.
function timeToMilliseconds($time) {
$dateTime = new DateTime($time);
$seconds = 0;
$seconds += $dateTime->format('H') * 3600;
$seconds += $dateTime->format('i') * 60;
$seconds += $dateTime->format('s');
$seconds = floatval($seconds . '.' . $dateTime->format('u'));
return $seconds * 1000;
}
Create function to convert GregorianDate to JulianDayCount
<?php
function dateJulian($date) {
$dateTime = new DateTime($date);
$limitDate = new DateTime('01-03-'.$dateTime->format('Y'));
$diff = $dateTime->diff($limitDate);
$soma = 1;
if ($dateTime->format('L') && $diff->invert) {
$soma = 2;
}
return ( (int) $dateTime->format('z')) + $soma;
}
echo PHP_EOL,dateJulian('01-03-2015'), PHP_EOL;
echo PHP_EOL,dateJulian('01-03-2016'), PHP_EOL;
/**
* returns
* 60
* 61
*/
?>
DateTime supports microseconds since 5.2.2. This is mentioned in the documentation for the date function, but bears repeating here. You can create a DateTime with fractional seconds and retrieve that value using the 'u' format string.
<?php
// Instantiate a DateTime with microseconds.
$d = new DateTime('2011-01-01T15:03:01.012345Z');
// Output the microseconds.
echo $d->format('u'); // 012345
// Output the date with microseconds.
echo $d->format('Y-m-d\TH:i:s.u'); // 2011-01-01T15:03:01.012345
This is a great class, but unless you need to use it's more advanced features, I would stick to passing times around your scripts as Unix Time Stamps - maybe prefixing with "uts".
Otherwise you will simply be creating more lines of code with no benefit.
It seems like, due to changes in the DateTimeZone class in PHP 5.5, when creating a date and specifying the timezone as a a string like 'EDT', then getting the timezone from the date object and trying to use that to set the timezone on a date object you will have problems but never know it. Take the following code:
<?php
$date = new DateTime('2015-08-21 15:00:00 EDT') ;
$tz_string = $date->getTimezone()->getName() ;
$tz = new DateTimeZone($tz_string) ;
$date->setTimezone($tz) ;
?>
You would think this code should not change $date at all, but it does. It seems like you can create a timezone object like 'EDT' but can't use those to set timezones properly. The process, however does act like it's working without errors.
Be aware of this behaviour:
<?php
$dt1 = new \DateTime( '2014/12/31' );
$dt1->modify( '-1 month' );
$m = (int) $dt1->format( 'm' );
var_dump( $m ); // still 12 !!!
$dt2 = new \DateTime( '2014/12/30' );
$dt2->modify( '-1 month' );
$m = (int) $dt2->format( 'm' );
var_dump( $m ); // 11
?>
The method modify( '-1 month' ) appear to remove 30 days, not to subtract 1 from the month and adjust the day (if needed).
In my opinion, the former date should be adjusted to 2014/11/30, that is, the last day in the previous month.
It isn't obvious from the above, but you can insert a letter of the alphabet directly into the date string by escaping it with a backslash in the format string. Note that if you are using "double" speech marks around the format string, you will have to further escape each backslash with another backslash! If you are using 'single' speech marks around the format string, then you only need one backslash.
For instance, to create a string like "Y2014M01D29T1633", you *could* use string concatenation like so:
<?php
$dtstring = "Y" . date("Y", $when) . "M" . date("m", $when) . "D" . date("d", $when) . "T" . date("Hi", $when);
?>
but you could also escape the letters with backslashes like so:
<?php
$dtstring1 = date('\YY\Mm\Dd\THi', $when);
$dtstring2 = date("\\YY\\Mm\\Dd\\THi", $when);
?>
This method involves fewer function calls, so probably is slightly quicker; and also is immune to race conditions if you are not specifying the second argument. [It's possible that you could evaluate date("d") just *before* midnight and date("H") just *after* midnight. This will not give you the result you were expecting.]
This caused some confusion with a blog I was working on and just wanted to make other people aware of this. If you use createFromFormat to turn a date into a timestamp it will include the current time. For example:
<?php
$publishDate = DateTime::createFromFormat('m/d/Y', '1/10/2014');
echo $publishDate->getTimestamp();
?>
Would not output the expected "1389312000" instead it would output something more like "1389344025". To fix this you would want to do:
<?php
$publishDate = DateTime::createFromFormat('m/d/Y', '1/10/2014');
$publishDate->setTime(0, 0, 0);
echo $publishDate->getTimestamp();
?>
I hope this helps someone!
Be aware that DateTime may ignore fractional seconds for some formats, but not when using the ISO 8601 time format, as documented by this bug:
https://bugs.php.net/bug.php?id=51950
$dateTime = DateTime::createFromFormat(
DateTime::ISO8601,
'2009-04-16T12:07:23.596Z'
);
// bool(false)
There is a subtle difference between the following two statments which causes JavaScript's Date object on iPhones to fail.
<?php
$objDateTime = new DateTime('NOW');
echo $objDateTime->format('c'); // ISO8601 formated datetime
echo $objDateTime->format(DateTime::ISO8601); // Another way to get an ISO8601 formatted string
/**
On my local machine this results in:
2013-03-01T16:15:09+01:00
2013-03-01T16:15:09+0100
Both of these strings are valid ISO8601 datetime strings, but the latter is not accepted by the constructor of JavaScript's date object on iPhone. (Possibly other browsers as well)
*/
?>
Our solution was to create the following constant on our DateHelper object.
<?php
class DateHelper
{
/**
* An ISO8601 format string for PHP's date functions that's compatible with JavaScript's Date's constructor method
* Example: 2013-04-12T16:40:00-04:00
*
* PHP's ISO8601 constant doesn't add the colon to the timezone offset which is required for iPhone
**/
const ISO8601 = 'Y-m-d\TH:i:sP';
}
?>
DateTime class does not use locales so here I test and compare its formating with strftime() function's one:
<?php
// Under UNIX, command "$ locale -a" should provide you with your server's options.
$data_do_mysql = "2011-09-29 23:50:26";
echo '<strong>' . "\$data_do_mysql" . '</strong>' . ":" . $data_do_mysql . "." . '<br />' .
'<br />';
$dataInicial = new DateTime(trim($data_do_mysql));
// setlocale() used with strftime().
$meu_locale = setlocale(LC_ALL, "pt_BR.utf8");
$data_inicial = strftime("%d de %b de %Y", strtotime(trim($data_do_mysql)));
// Outputs:
// $data_do_mysql formatada com a classe DateTime:29-Sep-2011.
echo '<strong>' . "\$data_do_mysql" . '</strong>' . " formatada com a classe DateTime:" . $dataInicial->format('d-M-Y') . "." . '<br />' .
'<br />';
// Outputs:
// $data_do_mysql formatada com a fun??o strftime():29 de Set de 2011.
echo '<strong>' . "\$data_do_mysql" . '</strong>' . " formatada com a função strftime():" . $data_inicial . "." . '<br />' .
'<br />';
// setlocale() fails :-(
if (!$meu_locale)
{
echo "Prefiro usar DateTime.";
}
// Yay setlocale() :-D
else
{
echo "Prefiro usar strftime().";
}
exit();
?>
IF You want to create clone of $time, use clone..
<?php
$now = new DateTime;
$clone = $now; //this doesnot clone so:
$clone->modify( '-1 day' );
echo $now->format( 'd-m-Y' ), "\n", $clone->format( 'd-m-Y' );
echo '----', "\n";
// will print same.. if you want to clone make like this:
$now = new DateTime;
$clone = clone $now;
$clone->modify( '-1 day' );
echo $now->format( 'd-m-Y' ), "\n", $clone->format( 'd-m-Y' );
?>
Results:
18-07-2011
18-07-2011
----
19-07-2011
18-07-2011
please note that using
setTimezone
setTimestamp
setDate
setTime
etc..
will modify the original object, and the return value is $this
$original = new DateTime("now");
$modified = $original->setTimezone(new DateTimezone("europe/rome"));
echo $original === $modified ? "THE OBJECT IS THE SAME" : "OBJECTS ARE DIFFERENT";
so a datetime object is mutable
(Editors note: PHP 5.5 adds DateTimeImmutable which does not modify the original object, instead creating a new instance.)
If you have timezone information in the time string you construct the DateTime object with, you cannot add an extra timezone in the constructor. It will ignore the timezone information in the time string:
$date = new DateTime("2010-07-05T06:00:00Z", new DateTimeZone("Europe/Amsterdam"));
will create a DateTime object set to "2010-07-05 06:00:00+0200" (+2 being the TZ offset for Europe/Amsterdam)
To get this done, you will need to set the timezone separately:
$date = new DateTime("2010-07-05T06:00:00Z");
$date->setTimeZone(new DateTimeZone("Europe/Amsterdam");
This will create a DateTime object set to "2010-07-05 08:00:00+0200"
If you need DateTime::createFromFormat functionality in versions <5.3.0 releases you might use the following basic class which can also be combined with Tom's class. It should work for most basic formats, however you should improve this function if you need more complex formats.
<?php
class DateClass extends DateTime{
public function getTimestamp(){
return $this->format ("U");
}
/**
* This function calculates the number of days between the first and the second date. Arguments must be subclasses of DateTime
**/
static function differenceInDays ($firstDate, $secondDate){
$firstDateTimeStamp = $firstDate->format("U");
$secondDateTimeStamp = $secondDate->format("U");
$rv = round ((($firstDateTimeStamp - $secondDateTimeStamp))/86400);
return $rv;
}
/**
* This function returns an object of DateClass from $time in format $format. See date() for possible values for $format
**/
static function createFromFormat ($format, $time){
assert ($format!="");
if($time==""){
return new DateClass();
}
$regexpArray['Y'] = "(?P<Y>19|20\d\d)";
$regexpArray['m'] = "(?P<m>0[1-9]|1[012])";
$regexpArray['d'] = "(?P<d>0[1-9]|[12][0-9]|3[01])";
$regexpArray['-'] = "[-]";
$regexpArray['.'] = "[\. /.]";
$regexpArray[':'] = "[:]";
$regexpArray['space'] = "[\s]";
$regexpArray['H'] = "(?P<H>0[0-9]|1[0-9]|2[0-3])";
$regexpArray['i'] = "(?P<i>[0-5][0-9])";
$regexpArray['s'] = "(?P<s>[0-5][0-9])";
$formatArray = str_split ($format);
$regex = "";
// create the regular expression
foreach($formatArray as $character){
if ($character==" ") $regex = $regex.$regexpArray['space'];
elseif (array_key_exists($character, $regexpArray)) $regex = $regex.$regexpArray[$character];
}
$regex = "/".$regex."/";
// get results for regualar expression
preg_match ($regex, $time, $result);
// create the init string for the new DateTime
$initString = $result['Y']."-".$result['m']."-".$result['d'];
// if no value for hours, minutes and seconds was found add 00:00:00
if (isset($result['H'])) $initString = $initString." ".$result['H'].":".$result['i'].":".$result['s'];
else {$initString = $initString." 00:00:00";}
$newDate = new DateClass ($initString);
return $newDate;
}
}
?>
Small but powerful extension to DateTime
<?php
class Blar_DateTime extends DateTime {
/**
* Return Date in ISO8601 format
*
* @return String
*/
public function __toString() {
return $this->format('Y-m-d H:i');
}
/**
* Return difference between $this and $now
*
* @param Datetime|String $now
* @return DateInterval
*/
public function diff($now = 'NOW') {
if(!($now instanceOf DateTime)) {
$now = new DateTime($now);
}
return parent::diff($now);
}
/**
* Return Age in Years
*
* @param Datetime|String $now
* @return Integer
*/
public function getAge($now = 'NOW') {
return $this->diff($now)->format('%y');
}
}
?>
Usage:
<?php
$birthday = new Blar_DateTime('1879-03-14');
// Example 1
echo $birthday;
// Result: 1879-03-14 00:00
// Example 2
echo '<p>Albert Einstein would now be ', $birthday->getAge(), ' years old.</p>';
// Result: <p>Albert Einstein would now be 130 years old.</p>
// Example 3
echo '<p>Albert Einstein would now be ', $birthday->diff()->format('%y Years, %m Months, %d Days'), ' old.</p>';
// Result: <p>Albert Einstein would now be 130 Years, 10 Months, 10 Days old.</p>
// Example 4
echo '<p>Albert Einstein was on 2010-10-10 ', $birthday->getAge('2010-10-10'), ' years old.</p>';
// Result: <p>Albert Einstein was on 2010-10-10 131 years old.</p>
?>
If you're stuck on a PHP 5.1 system (unfortunately one of my clients is on a rather horrible webhost who claims they cannot upgrade php) you can use this as a quick workaround:
<?php
if (!class_exists('DateTime')) {
class DateTime {
public $date;
public function __construct($date) {
$this->date = strtotime($date);
}
public function setTimeZone($timezone) {
return;
}
private function __getDate() {
return date(DATE_ATOM, $this->date);
}
public function modify($multiplier) {
$this->date = strtotime($this->__getDate() . ' ' . $multiplier);
}
public function format($format) {
return date($format, $this->date);
}
}
}
?>
it is NOT perfect. Timezones and DST are not supported, but if you just need compatible basic functions this works. Feel free to complete this so it's compatible with the 5.2 datetime object.