PHP - array_diff_ukey() Function

September 14, 2024

Categories: PHP Functions, PHP Reference, Reference

Quick Reference

The PHP array_diff_uassoc() function compares the keys of two or more arrays, and returns an array of entries from array1 not in the other array(s).

This function uses a user-defined function to compare the keys.

Only the keys are compared. Not the values.

<?php
function my_function($a, $b) {
    if ($a === $b) {
        return 0;
    }
    return ($a > $b)?1:-1;
}

$a1 = array('Car 1' => 'Lamborghini', 'Car 2' => 'Ferrari', 'Car 5' => 'Maserati');
$a2 = array('Car 1' => 'Lamborghini', 'Car 2' => 'Ferrari', 'Car 3' => 'Maserati');

$result = array_diff_uassoc($a1, $a2, 'my_function');
print_r($result);
?>

Note

Arrays count starting from zero NOT one. So item 1 is position [0], item 2 is position [1], and item 3 is position [2] … and so on.

Output

Array ( [Car 5] => Maserati )

Syntax

array_diff_ukey(array1, array2, array3, ..., my_function)

Parameters

Parameter	Description
array1	The array to compare from (required)
array2	The array to compare against (required)
array3, ...	Additional arrays to compare against
my_function	A string that defines a callable comparison function; the comparison function must return an integer <, =, or > than 0 if the first argument is <, =, or > than the second argument (required)

PHP Notes:

When using PHP, single or double quotation marks are acceptable and work identically to one another; choose whichever you prefer, and stay consistent
Arrays count starting from zero NOT one; so item 1 is position [0], item 2 is position [1], and item 3 is position [2] … and so on

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