To compare two arrays while considering duplicate value

Question

i have two arrays

$array1 = array(1, 2,  2, 3);
$array2 = array( 1, 2,  3,4);

and when did :

var_dump(array_diff($array1,         


        

Answer 1

This will get you the desired result:

$array1 = array(1, 2,  2, 3);
$array2 = array( 1, 2,  3,4);

$countArray1 = array_count_values($array1);
$countArray2 = array_count_values($array2);

foreach($countArray1 as $value=>$count) {
    if($count > 1) $dupArray[] = $value;
}

foreach($countArray2 as $value=>$count) {
    if($count > 1) $dupArray[] = $value;
}

print_r($dupArray);

Result

Array
(
    [0] => 2
)

Explanation

Using array_count_values will count all the values of an array, which would look like:

Array
(
    [1] => 1
    [2] => 2
    [3] => 1
)

Array
(
    [1] => 1
    [2] => 1
    [3] => 1
    [4] => 1
)

We then iterate through each array_count_values to locate values that occur more than once. This will work when you have more than one set of duplicate values:

$array1 = array(1, 2,  2, 3);
$array2 = array( 1, 2,  3, 4, 3);

Result

Array
(
    [0] => 2
    [1] => 3
)