array_intersect_uassoc()

array_intersect_uassoc() — Computes the intersection of arrays with additional index check, compares indexes by a callback function.

Built-in function of PHP 8.5. The manual lists it as available in PHP 5, PHP 7, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

What it does

array_intersect_uassoc() returns an array containing all the values of array that are present in all the arguments. Note that the keys are used in the comparison unlike in array_intersect().

Signature

array_intersect_uassoc(array $array, array ...$arrays, callable $key_compare_func): array callback(mixed $a, mixed $b): int

Parameters

Parameter	Type	What it takes
$array	array	Initial array for comparison of the arrays.
...$arrays	array	Arrays to compare keys against.
$key_compare_func	callable	The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.

Return value

Returns the values of array whose values exist in all of the arguments.

Example

A runnable snippet:

$array1 = array("a" => "green", "b" => "brown", "c" => "blue", "red"); $array2 = array("a" => "GREEN", "B" => "brown", "yellow", "red"); print_r(array_intersect_uassoc($array1, $array2, "strcasecmp"));

Output:

Array ( [b] => brown )