Php/docs/function.uasort
uasort
(PHP 4, PHP 5, PHP 7)
uasort — Sort an array with a user-defined comparison function and maintain index association
Description
uasort
( array &$array
, callable $callback
) : bool
This function sorts an array such that array indices maintain their correlation with the array elements they are associated with, using a user-defined comparison function.
This is used mainly when sorting associative arrays where the actual element order is significant.
Note:
If two members compare as equal, their relative order in the sorted array is undefined.
Parameters
array- The input array.
callback- See usort() and uksort() for examples of user-defined comparison functions.
Return Values
Returns TRUE on success or FALSE on failure.
Examples
Example #1 Basic uasort() example
<?php// Comparison functionfunction cmp($a, $b) { if ($a == $b) { return 0; } return ($a < $b) ? -1 : 1;}// Array to be sorted$array = array('a' => 4, 'b' => 8, 'c' => -1, 'd' => -9, 'e' => 2, 'f' => 5, 'g' => 3, 'h' => -4);print_r($array);// Sort and print the resulting arrayuasort($array, 'cmp');print_r($array);?>
The above example will output:
Array
(
[a] => 4
[b] => 8
[c] => -1
[d] => -9
[e] => 2
[f] => 5
[g] => 3
[h] => -4
)
Array
(
[d] => -9
[h] => -4
[c] => -1
[e] => 2
[g] => 3
[a] => 4
[f] => 5
[b] => 8
)
See Also
- usort() - Sort an array by values using a user-defined comparison function
- The comparison of array sorting functions
