PHP：按子数组值对数组排序（降序）

Question

I am trying to sort an array by its inner array values.

What I am actually trying is to sort $main_array by the values of "aa", "bb", "cc" (no matter which key is it, only need sorting by the values which are not empty and in descending order). I checked for solution, but didn't find. Thanks in advance

Code:

$main_array = array( 

 array(
 "firstName" => "Alex",
 "age" => 35, 
 "score" => array("aa" => "", "bb" => "", "cc" => 180)
 ), 


 array(
 "firstName" => "Helena",
 "age" => 41, 
 "score" => array("aa" => 410, "bb" => "", "cc" => "")
 ),
 );

 function func($a, $b) {

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

    uasort($main_array, 'func');

    print_r($main_array);

Answer 1

You could sum your data using array_sum() , or array_max() :

function func($a, $b) {
    $suma = array_sum($a['score']); // or array_max
    $sumb = array_sum($b['score']); // or array_max
    if ($suma == $sumb) { return 0; }
    return ($suma < $sumb) ? 1 : -1 ;
    // or just : return $suma <=> $sumb ; // As of PHP 7
}
uasort($main_array, 'func');
print_r($main_array);

As pointed by @deceze, here is a shorter function using difference between values instead of comparing the three states (see comments below) :

function func($a, $b) {
    return array_sum($b['score']) - array_sum($a['score']);
}