Finding Array Differences Based on Specific Column Values

In this situation, where you want to compare arrays based on a nested value within each element, the standard array_diff() function may not suffice. To achieve this, you can leverage a custom comparison function in conjunction with array_udiff().

Implementing the Solution

1. Define a User-Defined Comparison Function:
   Create a custom comparison function that focuses on the 'ITEM' values you wish to compare.

function udiffCompare($a, $b)
{
    return $a['ITEM'] - $b['ITEM'];
}

2. Use array_udiff():
   Now, you can use array_udiff() to compare the arrays using your custom comparison function as a callback. This will give you the differences you seek.

$arrdiff = array_udiff($arr2, $arr1, 'udiffCompare');
print_r($arrdiff);

Expected Output:

The resulting array, $arrdiff, will contain the elements from the second array (arr2) that differ from the first array (arr1) based on the ITEM values. In this case, it will return:

Array
(
    [3] => Array
        (
            [ITEM] => 4
        )
)

This approach ensures that you can effectively compare and filter arrays based on specific column values, providing you with the desired results.