PHP 日期时间添加 6 个月和 1 年

Question

I have a date set using PHP datetime like this..

$originaldate = 2019-01-10 17:52:17
$converted = DateTime::createFromFormat("Y-m-d H:i:s", $originaldate);

The date is successfuly converted into a PHP DateTime object, now I am trying to add create 2 new dates that are 6 months and 1 year ahead of this date.

Whats the best way to achieve this?

Answer 1

Check out DateTime::add

$converted->add(new DateInterval("P18M")); // add 18 months

P18M means 18 month interval

Answer 2

You can clone the time to create a duplicate and use DateTime::modify to change the new date.

Try this;

$sixMonths = clone $converted;
$sixMonths->modify('+6 months');

$oneYear = clone $converted;
$oneYear->modify('+1 year');

Answer 3

You should look into php class DateInterval http://php.net/manual/en/class.dateinterval.php

Here's an example:

$converted = DateTime::createFromFormat("Y-m-d H:i:s", $originaldate); 
$converted1Year = $converted->add(new DateInterval("P1Y"));//add one year //object reference is the same so adding a year altered original object and a reference to it is passed back, not copied
$converted2 = DateTime::createFromFormat("Y-m-d H:i:s", $originaldate);
$converted6months = $converted2->add(new DateInterval("P6M")); // add 6 months

And as suggested in the comments here's the DateTimeImmutable equivalent:

$converted = DateTimeImmutable::createFromFormat("Y-m-d H:i:s", $originaldate); 
$converted1Year = $converted->add(new DateInterval("P1Y"));
$converted6Months = $converted->add(new DateInterval("P6M"));

Answer 4

 $converted = $converted->modify('+6 months'); $converted = $converted->modify('+1 year'); 

Answer 5

Like so:

   $sixMonths = date('Y-m-d', strtotime($converted. ' + 6 months'));
   $oneYear = date('Y-m-d', strtotime($converted. ' + 1 year'));

Answer 6

The format already default ("Ymd H:i:s") . You don't need to use CreateFromFormat, unless you are handle data from 3rd party. My suggestion for the code would be like this

$originaldate = '2019-01-10 17:52:17';
$converted = new DateTime( $originaldate ); //prefer like this
//DateTime::createFromFormat("Y-m-d H:i:s", $originaldate); //after browsing this is recomended

$date6Month = new DateTime( $originaldate );
$date1Year = new DateTime( $originaldate );
$dateBack = new DateTime( $originaldate );
//$date6Month = $date1Year = $dateBack= $converted;
//prefer to use different variable for every date. Not copy

echo "ori:".$converted ->format('Y-m-d H:i:s') . "\n"; 
//ori:2019-01-10 17:52:17

##6 month later
$date6Month ->add(new DateInterval('P6M'));
echo "6 month:".$date6Month ->format('Y-m-d H:i:s') . "\n";
//6 month:2019-07-10 17:52:17

##1 year later
$date1Year ->add(new DateInterval('P1Y'));
echo "1 year:".$date1Year ->format('Y-m-d H:i:s') . "\n";
//1 year:2020-01-10 17:52:17
//1 year:2020-07-10 17:52:17 (wrong if using copy main parameter)

$date1Year ->add(  DateInterval::createFromDateString('1 Years') );
echo "1 year (later):".$date1Year ->format('Y-m-d H:i:s') . "\n";
//1 year (later):2021-01-10 17:52:17
//1 year (later):2021-07-10 17:52:17 (wrong if using copy main parameter)

you can use DateInterval::createFromDateString for readable code than using format. My suggestion is to separated the variable not copy from the origin.

The format you can use on DateInterval

Start "P" when contain Day, Month and Year

Format	Info	Example
Y	Year	1Y
M	Month	3M
D	Day	5D

example: P1Y3M5D

Always Start "P" before "T" if not contain Day, Month and Year (PT1H). If not start it with "T"

Format	Info	Example
H	HOUR	1H
M	MINUTES	3M
S	SECONDS	5S
F	MICROSECOND (php7+)	5F

example: PT1H3M5S

wrong: T1H3M5S

other example (from link below)

date_default_timezone_set('America/Phoenix'); 
//is important to add when your time are detail
$date = new DateTime('2000-01-01');
$date->add(new DateInterval('P7Y5M4DT4H3M2S'));
echo $date->format('Y-m-d H:i:s') . "\n";
//2007-06-05 04:03:02

$originaldate = 2019-01-10 17:52:17
$dateBack = $dateBack2 = new DateTime( $originaldate );
//if you want to substract the value you can use this
$dateBack ->sub(new DateInterval('P1Y2M3DT1H4M1S'));
echo $dateBack ->format('Y-m-d H:i:s') . "\n";
//output: 2019-05-07 16:48:16

$dateBack2=$converted;
$formatDay='P1Y3M6D'; //only year, month and day 
$formatTime='T1H3M6S'; //only hour, minutes and seconds
$dateBack2 ->sub(new DateInterval( $formatDay.$formatTime ));
echo $dateBack ->format('Y-m-d H:i:s') . "\n";
//2018-02-01 15:45:10

as mention on the phpmanual, there is other format (microtime) that's not include on this example.

related link

• Date Time PHP
• Date Interval
• Format on Interval
• Date Interval create using String