how to convert y-m-d to d-m-y in php code example

Example 1: php convert us date to european

$originalDate = "2010-03-21";
$newDate = date("d-m-Y", strtotime($originalDate));

Example 2: php convert date from dd/mm/yyyy to yyyy-mm-dd

$date = DateTime::createFromFormat('d/m/Y', "24/04/2012");
echo $date->format('Y-m-d');