如何使用不带html5的字符串获取确切的日期？

This is the string "2/29/16" i want to use this to compute dates can you suggest a way to use this string as a date?

$string = '2/29/16';
$date = new DateTime($string);
echo $date->format('Y-m-d');

The output is

2016-02-29

On how to format a date object, read in the PHP manual

To format the today string:

$date = new DateTime();
echo $date->format('Y-m-d');

Result:

2016-02-26