sort array based on the dateTime in php

Question

Array
        (
            [0] => Array
                (
                    [dateTime] => 2011-10-18 0:0:00
                    [chanl1] => 20.7
                    [chanl2] => 45.4
                    [chanl3] => 
                )

            [1] => Array
                (
                    [dateTime] => 2011-10-18 0:15:00
                    [chanl1] => 20.7
                    [chanl2] => 45.4
                    [chanl3] => 
                )


            [2] => Array
                (
                    [dateTime] => 2011-10-18 00:14:00
                    [chanl1] => 20.7
                    [chanl2] => 33.8
                    [chanl3] => 
                )

            [3] => Array
                (
                    [dateTime] => 2011-10-18 00:29:00
                    [chanl1] => 20.6
                    [chanl2] => 33.9
                    [chanl3] => 
                )

I want to sort the above array based on the [dateTime], the final output should be:

Array
        (
            [0] => Array
                (
                    [dateTime] => 2011-10-18 0:0:00
                    [chanl1] => 20.7
                    [chanl2] => 45.4
                    [chanl3] => 
                )

            [1] => Array
                (
                    [dateTime] => 2011-10-18 00:14:00
                    [chanl1] => 20.7
                    [chanl2] => 33.8
                    [chanl3] => 
                )

            [2] => Array
                (
                    [dateTime] => 2011-10-18 0:15:00
                    [chanl1] => 20.7
                    [chanl2] => 45.4
                    [chanl3] => 
                )            

            [3] => Array
                (
                    [dateTime] => 2011-10-18 00:29:00
                    [chanl1] => 20.6
                    [chanl2] => 33.9
                    [chanl3] => 
                )

Is there anyone know how to do it? Thanks!

Answer 1

Use usort() function with custom comparator:

$arr = array(...);

usort($arr, function($a, $b) {
  $ad = new DateTime($a['dateTime']);
  $bd = new DateTime($b['dateTime']);

  if ($ad == $bd) {
    return 0;
  }

  return $ad < $bd ? -1 : 1;
});

DateTime class has overloaded comparison operators (<, >, ==).