PHP uksort() Function
Topic: PHP Array ReferencePrev|Next
Description
The uksort() function sorts an array by keys using a user-defined comparison function.
The keys are preserved, i.e. the key-to-value mapping will remain unchanged by the sort operation.
The following table summarizes the technical details of this function.
| Return Value: | Returns TRUE on success or FALSE on failure. |
|---|---|
| Version: | PHP 4+ |
Syntax
The basic syntax of the uksort() function is given with:
The following example shows the uksort() function in action.
Example
Run this code »<?php
// Define comparison function
function compare($a, $b){
if($a == $b){
return 0;
}
return ($a < $b) ? -1 : 1;
}
// Sample array
$numbers = array("a"=>1, "c"=>2, "f"=>3, "d"=>4, "b"=>5, "e"=>6);
// Sort numbers array using compare function
uksort($numbers, "compare");
print_r($numbers);
?>The uksort() function is mainly used for sorting associative arrays by key. To sort an associative array by values using a user-defined comparison function use the uasort() function.
Note: The comparison function must return an integer equal to zero if both keys are equal, an integer less than zero if the first key is less than the second key, and an integer greater than zero if the first key is greater than the second key.
Parameters
The uksort() function accepts the following parameters.
| Parameter | Description |
|---|---|
| array | Required. Specifies the array to be sorted. |
| compare_function | Optional. Specifies the compare function to use for sorting. |
