DateInterval::createFromDateString ( string $time )
When the manual says "Uses the normal date parsers" it means that this function cannot take $time = ISO8601 strings like "P7D". If you want to use those, you must use the constructor.
(PHP 5 >= 5.3.0, PHP 7)
DateInterval::createFromDateString — Sets up a DateInterval from the relative parts of the string
Uses the normal date parsers and sets up a DateInterval from the relative parts of the parsed string.
timeA date with relative parts. Specifically, the relative formats supported by the parser used for strtotime() and DateTime will be used to construct the DateInterval.
Example #1 Parsing valid date intervals
<?php
// Each set of intervals is equal.
$i = new DateInterval('P1D');
$i = DateInterval::createFromDateString('1 day');
$i = new DateInterval('P2W');
$i = DateInterval::createFromDateString('2 weeks');
$i = new DateInterval('P3M');
$i = DateInterval::createFromDateString('3 months');
$i = new DateInterval('P4Y');
$i = DateInterval::createFromDateString('4 years');
$i = new DateInterval('P1Y1D');
$i = DateInterval::createFromDateString('1 year + 1 day');
$i = new DateInterval('P1DT12H');
$i = DateInterval::createFromDateString('1 day + 12 hours');
$i = new DateInterval('PT3600S');
$i = DateInterval::createFromDateString('3600 seconds');
?>
Returns a new DateInterval instance.
DateInterval::createFromDateString ( string $time )
When the manual says "Uses the normal date parsers" it means that this function cannot take $time = ISO8601 strings like "P7D". If you want to use those, you must use the constructor.
Sample usage:
<?php
$interval = DateInterval::createFromDateString('1 month');
?>