Sort multidimensional array by inner item...

Hi, I have this array (example):

$ar = array(
array("name" => "jane", "age" => 45),
array("name" => "rod", "age" => 50),
array("name" => "freddy", "age" => 40)
);

which print_r's this:

Array
(
    [0] => Array
        (
            [name] => jane
            [age] => 45
        )

    [1] => Array
        (
            [name] => rod
            [age] => 50
        )

    [2] => Array
        (
            [name] => freddy
            [age] => 40
        )

)

I need to sort the arrays by "age" to end up with this:

Array
(
    [0] => Array
        (
            [name] => rod
            [age] => 50
        )

    [1] => Array
        (
            [name] => jane
            [age] => 45
        )

    [2] => Array
        (
            [name] => freddy
            [age] => 40
        )

)

Any idea? If you need more info I'll try and explain further. Thanks!