Online PHP editor | output for fU5oH

<?php $dtArray = array(); $dtArray[] = new DateTime(); $dtArray[] = new DateTime(); foreach($dtArray as $value) { $value = null; } echo "object NOT reference: \n"; var_dump($dtArray); $dtArrayRef = array(); $dtArrayRef[] = new DateTime(); $dtArrayRef[] = new DateTime(); foreach($dtArrayRef as &$value) { $value = null; } echo "object REFERENCE: \n" var_dump($dtArrayRef); $string = array(); $string[] = 'new DateTime();'; $string[] = 'new DateTime();'; foreach($string as $value) { $value = null; } echo "string NOT reference: \n" var_dump($string);