Opposite of array_intersect

Question

I'm looking for the opposite of the function array_intersect, basically a function that returns the element that are not present in each of the provided arrays.

Example:

$a1 = array(1, 2, 3);
$a2 = array(2, 3, 4);
$result = array(1, 4);

I know how to do it programmatically (I just have two array so array_merge(array_diff($a1, $a2), array_diff($a2, $a1)) would do the job), but I'd like to know whether there's a built-in function that I can't find.

Thanks.

Answer 1

Since array_diff($a, $b) !== array_diff($b, $a) the inverse of array_intersect is:

array_merge(array_diff($a,$b), array_diff($b,$a));

Here it is in a PHPUnit test format:

class ArrayInverseTest {
    function testInverseArrayIntersect() {
        $a = array(1, 2, 3);
        $b = array(2, 3, 4);

        $this->assertEquals(
            array_values(array(1, 4)),
            array_values(array_merge(array_diff($a, $b), array_diff($b, $a)))
        );
    }
}