Sort array using multiple criteria in PHP

Question

I know there are some other topics about sorting with multiple criteria, but they don't fix my problem. Let's say I have this array:

Array
(
    [0] => Array
        (
            [uid] => 1
            [score] => 9
            [endgame] => 2
        )

    [1] => Array
        (
            [uid] => 2
            [score] => 4
            [endgame] => 1
        )

    [2] => Array
        (
            [uid] => 3
            [score] => 4
            [endgame] => 100
        )

    [3] => Array
        (
            [uid] => 4
            [score] => 4
            [endgame] => 70
        )

)

I want to sort it, putting the one with the HIGHEST score on top. On same score, I want the one with the LOWEST endgame number on top. The sorting mechanisme should rank user1 on top, then user2, then 4 and then user3.

I use this sorting mechanisme:

function order_by_score_endgame($a, $b)
{
  if ($a['score'] == $b['score'])
  {
    // score is the same, sort by endgame
    if ($a['endgame'] == $b['endgame']) return 0;
    return $a['endgame'] == 'y' ? -1 : 1;
  }

  // sort the higher score first:
  return $a['score'] < $b['score'] ? 1 : -1;
}
usort($dummy, "order_by_score_endgame");

This gives me the following array:

Array
(
    [0] => Array
        (
            [uid] => 1
            [score] => 9
            [endgame] => 2
        )

    [1] => Array
        (
            [uid] => 3
            [score] => 4
            [endgame] => 100
        )

    [2] => Array
        (
            [uid] => 2
            [score] => 4
            [endgame] => 1
        )

    [3] => Array
        (
            [uid] => 4
            [score] => 4
            [endgame] => 70
        )

)

As you can see, the array isn't sorted properly... Anyone knows what I'm doing wrong? Thanks a lot!

I see... I found this sorting mechanisme on http://stackoverflow.com/questions/3606156/sort-an-associative-array-in-php-with-multiple-condition , makes sence there since the head-values are "y" or "n". Is there an easy fix for my particular question? I just can't understand this sorting with multiple criteria... even after reading the manual and other threads about this... — binoculars, Jul 03 '14 at 16:42
Closing this as duplicate of the canonical explanation. Please read it, it should explain how sorting works and enable you to fix your code. — deceze, Jul 03 '14 at 16:44

score 18 · Accepted Answer · edited Apr 16 '21 at 16:18

Your function should be like this:

function order_by_score_endgame($a, $b) {
    if ($a['score'] == $b['score']) {
        // score is the same, sort by endgame
        if ($a['endgame'] > $b['endgame']) {
            return 1;
        }
    }

    // sort the higher score first:
    return $a['score'] < $b['score'] ? 1 : -1;
}

Try it out. It will give you result like this:

Array
(
[0] => Array
    (
        [uid] => 1
        [score] => 9
        [endgame] => 2
    )

[1] => Array
    (
        [uid] => 2
        [score] => 4
        [endgame] => 1
    )

[2] => Array
    (
        [uid] => 4
        [score] => 4
        [endgame] => 70
    )

[3] => Array
    (
        [uid] => 3
        [score] => 4
        [endgame] => 100
    )

)

Sort array using multiple criteria in PHP

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