array_diff_uassoc_vs_array_udiff_assoc.php

<?php

function compare_keys($a, $b) {
	if(abs($a) == abs($b)) return 0;
	return (abs($a) > abs($b))?1:-1;
}

function compare_values($a, $b){
	$tempA = is_array($a)?$a[0]:$a;
	$tempB = is_array($b)?$b[0]:$b;
	if($tempA == $tempB) return 0;
	return ($tempA > $tempB)?1:-1;
}

$test1 = array(
	1	=>	"a",
	2	=>	"b",
	3	=>	"c"
);

$test2 = array(
	-1	=>	"a",
	-2	=>	"b",
	-3	=> 	"c"
);

$test3 = array(
	1	=>	array("a"),
	2	=>	array("b"),
	3	=>	array("c")
);

/** Test 1
 * We are find the difference between arrays $test1 and $test2
 * array_diff_uassoc will use the compare_keys function for the keys and check the values for equality and 
 * array_udiff_assoc will use the compare_keys function for the values and check the keys for equality.
 * The compare_keys function compares the absolute values of the parameter. Therefore, when we use array_diff_uassoc
 * it is like comparing identical arrays and we should get an empty result. 
 */

echo "<hr/>Test 1<hr/><br/>";

echo "array_diff_uassoc<br/><pre>";
print_r(array_diff_uassoc($test1, $test2, "compare_keys"));
/*
Array
(
)
*/


echo "</pre><hr/>array_udiff_assoc<br/><pre>";
print_r(array_udiff_assoc($test1, $test2, "compare_keys"));
/*
Array
(
    [1] => a
    [2] => b
    [3] => c
)
*/

/** Test 2
 * We are going to find the differences between arrays $test1 and $.
 * array_diff_uassoc will check the values for equality and compare the keys with the function compare_values. 
 * Therefore, we should get the entire contents of $test1 back.
 * 
 * array_udiff_assoc will check the keys for equality and compare the values with the function compare_values.
 * This function checks if the parameters are arrays and if so uses the first value. 
 * For example, if "a" is compared to array("a"), the returned value would be 0.
 */

echo "</pre><br/><hr/>Test 2<hr/><br/>";
	
echo "array_diff_uassoc<br/><pre>";
print_r(array_diff_uassoc($test1, $test3, "compare_values"));
/*
Array
(
    [1] => a
    [2] => b
    [3] => c
)
*/

echo "</pre><hr/>array_udiff_assoc<br/><pre>";
print_r(array_udiff_assoc($test1, $test3, "compare_values"));
/*
Array
(

)
*/

?>