PHP usort by ascending array value

Question

Below is partial of my array

I tried to use the function below to sort it to order by page ascending However it seems rumble around, the page are not in increment state.

I not sure what's wrong with my sorting comparator function (cmp)

function cmp($a, $b) {
    return $a['page'] - $b['page'];
}


usort($chapter_result_array,"cmp");
$chapter_result_array = array_reverse($chapter_result_array);



[11] => Array
    (
        [link] => https://www.mywebsite.com/projects/funny-story/chapter-8-1.1046/
        [page] => 8.1
    )

[12] => Array
    (
        [link] => https://www.mywebsite.com/projects/funny-story/chapter-8-2.1085/
        [page] => 8.2
    )

[13] => Array
    (
        [link] => https://www.mywebsite.com/projects/funny-story/chapter-9-1.1114/
        [page] => 9.1
    )

[14] => Array
    (
        [link] => https://www.mywebsite.com/projects/funny-story/chapter-6-1.890/
        [page] => 6.1
    )

[15] => Array
    (
        [link] => https://www.mywebsite.com/projects/funny-story/chapter-6-2.995/
        [page] => 6.2
    )

[16] => Array
    (
        [link] => https://www.mywebsite.com/projects/funny-story/chapter-7-1.1020/
        [page] => 7.1
    )

[17] => Array
    (
        [link] => https://www.mywebsite.com/projects/funny-story/chapter-5-1.855/
        [page] => 5.1
    )

not sure, what you want. Its better to give your desire output, so we can clear what you really want. — Murad Hasan
– Murad Hasan, Commented Mar 27, 2016 at 9:05
Note that the manual says that "The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second." — Gralgrathor
– Gralgrathor, Commented Mar 27, 2016 at 9:57
Eh... something like "return ($a < $b) ? -1 : ($a > $b) ? 1 : 0;"? Or any rounding function, if you know what the range of your input is going to be. — Gralgrathor
– Gralgrathor, Commented Mar 27, 2016 at 10:15
Once you have it working if you follow @Gralgrathor's advice and you want them in reverse order you can swap -1 with 1 in your function rather than call array_reverse afterwards. — Matt Raines
– Matt Raines, Commented Mar 27, 2016 at 15:48

Community · Accepted Answer · 2017-05-23 11:59:34Z

0

I guess the pages are not float values but more like "version strings" so you should compare with version compare: Compare two version strings in PHP

It will return you -1, 0 or 1 like usort is intented to be used.

edited May 23, 2017 at 11:59

CommunityBot

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answered Mar 27, 2016 at 10:19

Fabien Ménager

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