What does 'P' stand for in the DateInterval format?
PhpPhp 5.3Php Problem Overview
Consider the following example quoted from php manual for DateTime
<?php
$date = new DateTime('2000-01-20');
$date->sub(new DateInterval('P10D'));
echo $date->format('Y-m-d') . "\n";
?>
'D' is for days, what does the 'P' stand for in that formatting?
Php Solutions
Solution 1 - Php
From the manual
> Interval specification. > > The format starts with the letter P, for "period." Each duration period is represented by an integer value followed by a period designator. If the duration contains time elements, that portion of the specification is preceded by the letter T.
Solution 2 - Php
'P' stands for Period. see here <http://php.net/manual/en/dateinterval.construct.php>
Solution 3 - Php
I think it can be answered in more details. First of all, DateInterval constructor method takes one parameter named $interval_spec which is string.
DateInterval::__construct ( string $interval_spec )
This parameter has a specification described as below:
> The format starts with the letter P, for period. Each duration period > is represented by an integer value followed by a period designator. If > the duration contains time elements, that portion of the specification > is preceded by the letter T.
There are some Period Designators that are used in the argument:
- Y for years
- M for months
- D for days
- W for weeks. These get converted into days, so can not be combined with D.
- H for hours
- M for minutes
- S for seconds
Let's see some example using Period Designators:
- Two days is P2D.
- Two seconds is PT2S.
- Six years and five minutes is P6YT5M.
There is an order that needs to be maintained as described the doc:
> The unit types must be entered from the largest scale unit on the left > to the smallest scale unit on the right. So years before months, > months before days, days before minutes, etc. Thus one year and four > days must be represented as P1Y4D, not P4D1Y.
The specification can also be represented as a datetime.
- One year, two months, four days would be P0001-02-04T00:00:00
But the values in this format can not exceed a given period's roll-over-point (e.g. 25 hours is invalid).