Online PHP editor | refs for SXI6Br

<?php $first = [ '01-1970' => 0.00, '03-2019' => 4350.00, '05-2019' => 150.00, '06-2019' => 50.00, ]; $second = [ '03-2019' => 0.00, '04-2019' => 0.00, '06-2019' => 34.83, ]; $result = $first; foreach ($second as $k => $v) { $result[$k] = ($result[$k] ?? 0) + $v; } uksort( $result, fn($a, $b) => preg_replace('/(\d+)-(\d+)/', '$2-$1', $a) <=> preg_replace('/(\d+)-(\d+)/', '$2-$1', $b) ); var_export($result);