How can you ensure that elements that appear more than once in two arrays are no longer present in the final list?

To ensure that elements that appear more than once in two arrays are not present in the final list, we can merge the two arrays, remove duplicates, and then filter out elements that have a count greater than 1. This way, we will only have unique elements from both arrays in the final list.

$array1 = [1, 2, 3, 4, 5];
$array2 = [3, 4, 5, 6, 7];

// Merge the two arrays and remove duplicates
$mergedArray = array_unique(array_merge($array1, $array2));

// Filter out elements that appear more than once
$finalList = array_filter($mergedArray, function($value) use ($mergedArray) {
    return array_count_values($mergedArray)[$value] == 1;
});

print_r($finalList);