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.
Returning non-integer values from the comparison
function, such as float, will result in an internal cast to
int of the callback's return value. So values such as
0.99 and 0.1 will both be cast to an
integer value of 0, which will compare such values as equal.
Caution
The sorting callback must handle any value from any array in any order,
regardless of the order they were originally provided.
This is because each individual array is first sorted before being compared against other arrays.
For example:
<?php
$arrayA = ["string", 1];
$arrayB = [["value" => 1]];
// $item1 and $item2 can be any of "string", 1 or ["value" => 1]
$compareFunc = static function ($item1, $item2) {
$value1 = is_string($item1) ? strlen($item1) : (is_array($item1) ? $item1["value"] : $item1);
$value2 = is_string($item2) ? strlen($item2) : (is_array($item2) ? $item2["value"] : $item2);
return $value1 <=> $value2;
};
?>
key_compare_func
The comparison of keys (indices) is done also by the callback function
key_compare_func. This behaviour is unlike what
array_udiff_assoc() does, since the latter compares
the indices by using an internal function.
Return Values
Returns an array containing all the values from
array that are not present in any of the other
arguments.
Examples
Example #1 array_udiff_uassoc() example
<?php
class cr {
private $priv_member;
function __construct($val)
{
$this->priv_member = $val;
}
static function comp_func_cr($a, $b)
{
if ($a->priv_member === $b->priv_member) return 0;
return ($a->priv_member > $b->priv_member)? 1:-1;
}
static function comp_func_key($a, $b)
{
if ($a === $b) return 0;
return ($a > $b)? 1:-1;
}
}
$a = array("0.1" => new cr(9), "0.5" => new cr(12), 0 => new cr(23), 1=> new cr(4), 2 => new cr(-15),);
$b = array("0.2" => new cr(9), "0.5" => new cr(22), 0 => new cr(3), 1=> new cr(4), 2 => new cr(-15),);
$result = array_udiff_uassoc($a, $b, array("cr", "comp_func_cr"), array("cr", "comp_func_key"));
print_r($result);
?>
In our example above you see the "1" => new cr(4)
pair is present in both arrays and thus it is not in the output from the
function. Keep in mind that you have to supply 2 callback functions.
Notes
Note:
Please note that this function only checks one dimension of a n-dimensional
array. Of course you can check deeper dimensions by using, for example,
array_udiff_uassoc($array1[0], $array2[0], "data_compare_func",
"key_compare_func");.
array_udiff_assoc
Array Functions