The uksort() function is a built-in function in PHP and is used to sort an array according to the keys and not values using a user-defined comparison function.
Syntax:
boolean uksort($array, myFunction);
Parameter: This function accepts two parameters and are described below:
- $array: This parameter specifies an array which we need to sort.
- myFunction: This parameter specifies name of a user-defined function which will be used to sort the keys of array $array. This comparison function must return an integer.
Return value: This function returns a boolean value. It returns TRUE on success or FALSE on failure.
Below programs illustrate the uksort() function in PHP:
Program 1:
<?php   // user-defined comparison function function my_sort($x, $y) {     if ($x == $y)         return 0;       return ($x > $y) ? -1 : 1; }   // Input array $names = array(                 "10" => "javascript",                 "20" => "php",                 "60" => "vbscript",                 "40" => "jsp"              );   uksort($names, "my_sort");   // printing sorted array print_r ($names); ?> |
Output:
Array
(
[60] => vbscript
[40] => jsp
[20] => php
[10] => javascript
)
Program 2:
<?php   // user-defined comparison function function my_sort($x, $y) {     if ($x == $y)         return 0;       return ($x > $y) ? 1 : -1; }   // Input array $names = array(                 "10" => "javascript",                 "20" => "php",                 "60" => "vbscript",                 "40" => "jsp"              );   uksort($names, "my_sort");   // printing sorted array print_r ($names); ?> |
Output:
Array
(
[10] => javascript
[20] => php
[40] => jsp
[60] => vbscript
)
Note: If two values are compared as equal according to the user-defined comparison function then their order in the output array will be undefined.
Reference:
http://php.net/manual/en/function.uksort.php
