Question

I’ve got the following Php script:

<?php
function filt($k, $l){
    if($k===$l){
        var_dump("valid: ".$k."-".$l);
        return 0;
    }
    return 1;
}
$a6=array(7, 9, 3, 33);
$a7=array(2, 9, 3, 33);
$u=array_udiff($a6, $a7, "filt");
var_dump($u);
?>

With the following output:

string 'valid: 3-3' (length=10)

array
    0 => int 7
    1 => int 9
    3 => int 33

As I know, the array_udiff should dump the equal values and let only the different values from the first array.
What seems to be the problem here?
I run WampServer Version 2.2 on Windows 7. Php version: 5.3.9.

Answer 1

you’re not returning all necessary values (e.g. -1, 0, 1). See: array_udiff

$a6 = array(7, 9, 3, 33);
$a7 = array(2, 9, 3, 33);

$u = array_udiff($a6, $a7, function ($k, $l){
  return $k > $l ? 1 : ($k < $l ? -1 : 0);
});

print_r($u);