Question

I have an array of strings that I want to sort in order of descending length. However, it is a two dimensional array and I’m not sure how to implement a function which will do what I want.

Here is an example of the array:

Array
(
  [0] => Array
    (
      [0] => "abc"
      [1] => "def"
      [2] => "1234"
    )

  [1] => Array
    (
      [0] => "ghijkl"
      [1] => "092"
      [2] => "234234"
    )

  [2] => Array
    (
      [0] => "mn"
      [1] => "opq"
      [2] => "67843"
    )
)

I’m only interested in the length of the first item in the sub-arrays. So ideally it will end up looking like this:

Array
(
  [0] => Array
    (
      [0] => "ghijkl"
      [1] => "092"
      [2] => "234234"
    )
  [1] => Array
    (
      [0] => "abc"
      [1] => "def"
      [2] => "1234"
    )
  [2] => Array
    (
      [0] => "mn"
      [1] => "opq"
      [2] => "67843"
    )
)

Cheers for any help you can give me.

Answer 1

usort($array, function ($a, $b) { return strlen($b[0]) - strlen($a[0]); });

(uses PHP 5.3 syntax)