PHP array_uintersect

array_uintersect_assoc(): custom value comparison with key checks

array_uintersect_assoc() compares values through your callback while also requiring the array keys to match using the normal key comparison.

$first = ['a' => 'RED', 'b' => 'green'];
$second = ['a' => 'red', 'b' => 'blue'];
$result = array_uintersect_assoc($first, $second, 'strcasecmp');
print_r($result);

Keys are checked normally; only the value comparison uses your callback.

The array_uintersect_assoc() function in PHP returns the intersection of arrays with additional index association checks. A user-defined callback function is used for value comparison. The function compares both keys and values, making it useful when both are important in your intersection logic.

Syntax

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

Example 1: Simple Array Intersection with Index Comparison

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

$array1 = ['a' => 'Apple', 'b' => 'Banana', 'c' => 'Cherry'];
$array2 = ['a' => 'apple', 'b' => 'Banana', 'c' => 'cherry'];

$result = array_uintersect_assoc($array1, $array2, 'compare_values');
print_r($result);

Output

Array
(
    [b] => Banana
)

Example 2: Numeric Array Intersection with Custom Comparison

function num_compare($a, $b) {
    return $a <=> $b;
}

$array1 = [0 => 10, 1 => 20, 2 => 30];
$array2 = [0 => 10, 2 => 30, 3 => 40];

$result = array_uintersect_assoc($array1, $array2, 'num_compare');
print_r($result);

Output

Array
(
    [0] => 10
    [2] => 30
)

Conclusion

The array_uintersect_assoc() function is ideal for cases where both key and value need to be considered during intersection, providing more control with the custom comparison callback.
array_uintersect_uassoc(): custom intersection of arrays with user-defined key and value comparisons
Filling an array with value
Array REFERENCE

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array_uintersect_assoc(): array intersections with custom value comparison