Question

I need to sort this array by distance

Array
(
    [0] => Array
        (
            [name] => Pyro Pizza
            [distance] => 2.3
        )

    [1] => Array
        (
            [name] => Sparky's Pizza
            [distance] => 2.1
        )

    [2] => Array
        (
            [name] => American Dream Pizza - Portland
            [distance] => 0.5
        )

    [3] => Array
        (
            [name] => Ken's Artisan Pizza
            [distance] => 1.1
        )

    [4] => Array
        (
            [name] => Sparky's Pizza - SE
            [distance] => 2.2
        )

    [5] => Array
        (
            [name] => Vincente's Gourmet Pizza and the V-Room
            [distance] => 2
        )

    [6] => Array
        (
            [name] => Blind Onion Pizza and Pub
            [distance] => 0.6
        )

    [7] => Array
        (
            [name] => Hot Lips Pizza
            [distance] => 1.9
        )

    [8] => Array
        (
            [name] => Flying Pie Pizzeria
            [distance] => 2
        )

    [9] => Array
        (
            [name] => Hammy's Pizza
            [distance] => 2.4
        )

)

I used this..

usort($results, 'sortByOrder');

with this..

function sortByOrder($a, $b) {
    return $a['distance'] - $b['distance'];
}

but it doesn’t work

Answer 1

This should do the job:

function sortByOrder($a, $b) {
    if ( $a ['distance'] == $b ['distance'] ) return 0;
    return ( $a ['distance'] < $b ['distance'] ) ? -1 : 1;
}

usort ( $results, 'sortByOrder' );

The problem with your code is that the comparison function, sortByOrder here, should return either 0 if they are equal or -1/1 if one of them is bigger. Your function however returned the difference in distance, which usort() can’t parse.