PHP multi sort array

Question

If I have this array:

array(
    [0] => array(5, "hi"),
    [1] => array(2, "hello"),
    [2] => array(9, "test")
)

How can I sort this array by [n][0]?
The end result should to be like this:

array(
    [0] => array(9, "test")
    [1] => array(5, "hi"),
    [2] => array(2, "hello"),
)

Answer 1

You can use a custom comparison function:

function multi_sort($a, $b)
{
    return $a[0] < $b[0];
}

usort($array, 'multi_sort');