- var_dump: documentation ( source)
<?php
$months = [
'2023-04',
'2023-03',
'2023-04',
'2023-04',
'2023-02',
];
$amounts = [
833,
223,
829,
220,
498
];
$sums = [];
foreach($months as $i => $month) {
if (!isset($sums[$month])) {
$sums[$month] = 0;
}
$sums[$month] += $amounts[$i];
}
var_dump($sums);