Question

What would be the best practice to sort a list containing date and a unique identifier for the date, like so:

20110101 5
20110101 78
20150305 103

(That is YYYYMMDD Unique identifier).

I have tried making arrays in php, amongst others:

    [0] => Array
        (
            [date] => 20110101
            [order] => 3
        )

    [1] => Array
        (
            [date] => 20120101
            [order] => 2
        )

    [2] => Array
        (
            [title] => 20130101
            [order] => 1
        )
)

and

$data[] = array('date' => 20100101, 'number' => 122);
$data[] = array('date' => 20110123, 'number' => 120);
$data[] = array('date' => 20111212, 'number' => 123);
$data[] = array('date' => 20091212, 'number' => 121);
$data[] = array('date' => 20151212, 'number' => 100);
$data[] = array('date' => 20151212, 'number' => 99); 

but I can’t manage to get the PHP to print, well… anything using different sorting methods (like array_multisort).

What I would want to achieve is a list sorted by date and unique number. The second example would thus begin like:

20151212 100,
20151212 99,
20111212 123

I am mew and fresh to PHP, so please keep the answers at beginner level!

Thanks!!

Answer 1

The best way to attack the problem is by using a callback function to sort the entries by using usort

function cmp($a,$b){
  //do the necessary check if $a and $b conforms to your structure
  if($a['date'] < $b['date']) return -1;
  if($a['date'] > $b['date']) return 1;
  if($a['number'] > $b['number'] return 1;
  if($a['number'] < $b['number'] return -1;
  return 1;
}

usort($data,'cmp');