(PHP 5 >= 5.3.0, PHP 7, PHP 8)
DateInterval::createFromDateString — Sets up a DateInterval from the relative parts of the string
Uses the date/time parsers as used in the DateTimeImmutable constructor to create a DateInterval from the relative parts of the parsed string.
datetimeA date with relative parts. Specifically, the relative formats supported by the parser used for DateTimeImmutable, DateTime, and strtotime() will be used to construct the DateInterval.
       To use an ISO-8601 format string like P7D, you must
       use the constructor.
      
   Returns a new DateInterval instance on success,  or false on failure.
  
| Version | Description | 
|---|---|
| 8.2.0 | Only the from_stringanddate_stringproperties will be visible when a
       DateInterval is created with this method. | 
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');
?>
Example #2 Parsing combinations and negative intervals
<?php
$i = DateInterval::createFromDateString('62 weeks + 1 day + 2 weeks + 2 hours + 70 minutes');
echo $i->format('%d %h %i'), "\n";
$i = DateInterval::createFromDateString('1 year - 10 days');
echo $i->format('%y %d'), "\n";
?>
The above example will output:
Example #3 Parsing special relative date intervals
<?php
$i = DateInterval::createFromDateString('last day of next month');
var_dump($i);
$i = DateInterval::createFromDateString('last weekday');
var_dump($i);
Output of the above example in PHP 8.2:
object(DateInterval)#1 (2) {
  ["from_string"]=>
  bool(true)
  ["date_string"]=>
  string(22) "last day of next month"
}
object(DateInterval)#2 (2) {
  ["from_string"]=>
  bool(true)
  ["date_string"]=>
  string(12) "last weekday"
}
Output of the above example in PHP 8 is similar to:
object(DateInterval)#1 (16) {
  ["y"]=>
  int(0)
  ["m"]=>
  int(1)
  ["d"]=>
  int(0)
  ["h"]=>
  int(0)
  ["i"]=>
  int(0)
  ["s"]=>
  int(0)
  ["f"]=>
  float(0)
  ["weekday"]=>
  int(0)
  ["weekday_behavior"]=>
  int(0)
  ["first_last_day_of"]=>
  int(2)
  ["invert"]=>
  int(0)
  ["days"]=>
  bool(false)
  ["special_type"]=>
  int(0)
  ["special_amount"]=>
  int(0)
  ["have_weekday_relative"]=>
  int(0)
  ["have_special_relative"]=>
  int(0)
}
object(DateInterval)#2 (16) {
  ["y"]=>
  int(0)
  ["m"]=>
  int(0)
  ["d"]=>
  int(0)
  ["h"]=>
  int(0)
  ["i"]=>
  int(0)
  ["s"]=>
  int(0)
  ["f"]=>
  float(0)
  ["weekday"]=>
  int(0)
  ["weekday_behavior"]=>
  int(0)
  ["first_last_day_of"]=>
  int(0)
  ["invert"]=>
  int(0)
  ["days"]=>
  bool(false)
  ["special_type"]=>
  int(1)
  ["special_amount"]=>
  int(-1)
  ["have_weekday_relative"]=>
  int(0)
  ["have_special_relative"]=>
  int(1)
}