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PHP | ArrayIterator uksort() Function

The ArrayIterator::uksort() function is an inbuilt function in PHP which is used to sort the keys by using a user-defined comparison function.

Syntax:

void ArrayIterator::uksort( callable $cmp_function )

Parameters: This function accepts single parameter $cmp_function which holds the user defined comparison function.

Return Value: This function does not return any value.

Below programs illustrate the ArrayIterator::uksort() function in PHP:
Program 1:




<?php
  
// Declare an ArrayIterator
$arrItr = new ArrayIterator(
    array(
        "a" => 4,
        "b" => 2,
        "g" => 8,
        "d" => 6,
        "e" => 1,
        "f" => 9
    )
);
  
// User defined comparator function 
function sorting($a, $b) { 
    if($a == $b)
        return 0; 
    return ($a < $b) ? -1 : 1; 
} 
  
$arrItr->uksort("sorting"); 
    
// Printing the sorted array. 
print_r($arrItr); 
  
?>


Output:

ArrayIterator Object
(
    [storage:ArrayIterator:private] => Array
        (
            [a] => 4
            [b] => 2
            [d] => 6
            [e] => 1
            [f] => 9
            [g] => 8
        )

)

Program 2:




<?php
     
// Declare an ArrayIterator
$arrItr = new ArrayIterator(
    array(
        "b" => "for",
        "a" => "Geeks",
        "e" => "Science",
        "c" => "Geeks",
        "f" => "Portal",
        "d" => "Computer"
    )
);
    
// Declare a comparison function to sort  
// values in descending order 
function comparison($val1, $val2) { 
    if ($val1 == $val2) { 
        return 0; 
    } 
    else if($val1 > $val2) 
        return -1; 
    else
        return 1; 
} 
    
$arrItr->uksort('comparison'); 
    
// Print the sorted ArrayObject 
print_r($arrItr); 
  
?>


Output:

ArrayIterator Object
(
    [storage:ArrayIterator:private] => Array
        (
            [f] => Portal
            [e] => Science
            [d] => Computer
             => Geeks
            [b] => for
            [a] => Geeks
        )

)

Reference: https://www.php.net/manual/en/arrayiterator.uksort.php

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