- print_r: documentation ( source)
- array_filter: documentation ( source)
- array_unique: documentation ( source)
<?php
$allBills = [0, 0, 1, null];
$bills = array_unique($allBills);
if (count($bills) != 1) {
$bills = array_filter(
$bills,
function ($val) {
return is_null($val);
}
);
}
print_r($bills);