对数组进行排序并获取密钥

Question

I have two arrays First Array :

$array_1 = array('50','20','30');

Second Array :

$array_2 = array('50','30','20');

Second array is generating by applying rsort to $array_1

How can i get another array of key like

$key_array = ('0','2','1');

Answer 1

The rsort function will reindex your array keys:

Note: This function assigns new keys to the elements in array. It will remove any existing keys that may have been assigned, rather than just reordering the keys.

You can use arsort instead to maintain index associations. Then you can simply use array_keys to get your desired result.

$unsorted = [50, 20, 30];          // array with unsorted values
$in_reverse = $unsorted;           // create copy because arsort is by reference
arsort($in_reverse);               // do the actual sorting
$keys = array_keys($in_reverse);   // fetch the keys

print_r($keys); 

will output

Array
(
    [0] => 0
    [1] => 2
    [2] => 1
)