Online PHP editor | output for t9k6a

@ 2022-09-25T08:31:01Z

<?php

$array = [
    "Jan 2016" => 2,
    "Feb 2016" => 4,
    "Mar 2016" => 2,
    "Apr 2016" => 0,
    "Jan 2017" => 9,
    "Feb 2017" => 2,
    "Mar 2017" => 5,
    "Jan 2018" => 4,
    "Feb 2018" => 6
]; 

foreach ($array as $date => &$amount) {
    $year = substr($date, -4);
    $amount = ['month' => $amount, 'total' => &$ref[$year]];
    $ref[$year] = ($ref[$year] ?? 0) + $amount['month'];
}
var_export($array);

Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12: array ( 'Jan 2016' => array ( 'month' => 2, 'total' => 8, ), 'Feb 2016' => array ( 'month' => 4, 'total' => 8, ), 'Mar 2016' => array ( 'month' => 2, 'total' => 8, ), 'Apr 2016' => array ( 'month' => 0, 'total' => 8, ), 'Jan 2017' => array ( 'month' => 9, 'total' => 16, ), 'Feb 2017' => array ( 'month' => 2, 'total' => 16, ), 'Mar 2017' => array ( 'month' => 5, 'total' => 16, ), 'Jan 2018' => array ( 'month' => 4, 'total' => 10, ), 'Feb 2018' => array ( 'month' => 6, 'total' => 10, ), )

preferences:dark modelive previewkey bindings