php convert date dd/mm/yy code example

Example 1: php date format dd/mm/yyyy

date("d/m/Y", strtotime($str));

Example 2: php change date format from d/m/y to y-m-d

$var = '20/04/2012';
$date = str_replace('/', '-', $var);
echo date('Y-m-d', strtotime($date));