PHP array_uintersect_assoc: Compute Array Intersection with Index Check Using a Callback

Function signature

array array_uintersect_assoc (array $array1, array $array2, callable $data_compare_func)

Description

This function computes the intersection of $array1 and $array2 while preserving the keys of the first array. Comparison of values is performed by a user‑supplied callback function $data_compare_func, which must return an integer less than, equal to, or greater than zero when the first argument is considered less than, equal to, or greater than the second argument.

Parameters

array1 : The first array.

array2 : The second array.

data_compare_func : A callable that receives two values and returns an integer (<0, 0, >0) indicating the comparison result.

Return value

Returns an array containing all values from $array1 that are also present in $array2 (according to the comparison callback), preserving the original keys.

Example

<?php
$array1 = array(
    "a" => "green",
    "b" => "brown",
    "c" => "blue",
    "d" => "red"
);

$array2 = array(
    "a" => "GREEN",
    "b" => "brown",
    "c" => "yellow",
    "d" => "red"
);

print_r(array_uintersect_assoc($array1, $array2, "strcasecmp"));
?>

Output

Array
(
    [a] => green
)