Question

Ok i got a weird issue here.
Im trying to calculate the old date and the new date. However i spotted a issue that is unexplainable by me.

The setup :
I have 2 new dates set on today.

$tempstamp = new DateTime();
$newstamp = new DateTime();

Now, i edit the newstamp into a new date useing :

if ($newstamp ->format('His') > 120000) $newstamp ->modify('+7 day');
else $newstamp ->modify('+4 day');

Which works perfectly. However now comes the weird part.
When i dump both values before and after it the tempstamp gives a unexplainable value :

case '2':
  $tempstamp = $newstamp;

  dump($tempstamp->format('m-d')); // 02-19 - CORRECT
  dump($newstamp->format('m-d')); // 02-19 - CORRECT

  if ($newstamp->format('His') > 120000) $newstamp->modify('+7 day');
  else $newstamp->modify('+4 day');

  dump($tempstamp->format('m-d')); // 02-26 - FALSE
  dump($newstamp->format('m-d')); // 02-26 - CORRECT

*NOTE: dump is our way of var_dumping*

The Question:
Can someone explain why tempstamp is getting editted as well while i only edit newstamp?

Answer 1

PHP copies objects by reference, not by value. So $tempstamp = $newstamp; is now making $tempstamp and $newstamp point to the same object. To avoid this you need to use clone:

$tempstamp = clone $newstamp;