array_uintersect(): intersection of arrays with Custom Comparison

Syntax

array_uintersect(array $array1, array $array2, callable $callback): array

Example 1: Simple Intersection with Case-Insensitive Comparison

function caseInsensitiveCompare($a, $b) {
    return strcmp(strtolower($a), strtolower($b));
}

$array1 = ['APPLE', 'BANANA', 'CHERRY'];
$array2 = ['apple', 'ORANGE', 'cherry'];

$result = array_uintersect($array1, $array2, 'caseInsensitiveCompare');
print_r($result);

Array
(
    [0] => APPLE
    [2] => CHERRY
)

Example 2: Intersection of Numeric Arrays with Custom Comparison

function numCompare($a, $b) {
    return $a - $b;
}

$array1 = [1, 2, 3, 4];
$array2 = [3, 4, 5, 6];

$result = array_uintersect($array1, $array2, 'numCompare');
print_r($result);

Array
(
    [2] => 3
    [3] => 4
)

Conclusion