Sort array by date in descending order by date in php

Question

I have an array and I want to sort it by date. I am not able to sort it properly by date in descending order. Please help.

Array
(
[1] => Array
    (
        [1] => 11/05/2013
        [2] => Executive Planning Day
    )

[2] => Array
    (
        [1] => 13/06/2013
        [2] => Middle Leaders Planning Day
    )

[3] => Array
    (
        [1] => 12/07/2013
        [2] => New Staff Induction Day
    )

[4] => Array
    (
        [1] => 13/04/2013
        [2] => Staff Conference Day No. 1
    )

[5] => Array
    (
        [1] => 14/04/2013
        [2] => Staff Conference Day No. 2
    )

[6] => Array
    (
        [1] => 15/02/2013
        [2] => Staff Conference Day No. 3
    )

[7] => Array
    (
        [1] => 16/03/2013
        [2] => Australia Day
    )
)

Answer 1

Use usort(Sort an array by values using a user-defined comparison function).

usort($array, function($a1, $a2) {
   $value1 = strtotime($a1['date']);
   $value2 = strtotime($a2['date']);
   return $value1 - $value2;
});