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PHP | uksort() Function
  • Last Updated : 18 Mar, 2018


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:

  1. $array: This parameter specifies an array which we need to sort.
  2. 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

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