编辑代码

<?php 

echo date('Y', (strtotime(date('Y-m-01')) - 86400));

echo '<br />';

echo date('Y', strtotime('-1 year'));

echo '<br />';

print_r(array_diff([1,2,3,4,5,6], [2,3,4,5,6,7,8,9,10,11,12]));

echo '<br />';

function sumArrays(array $arrays = null,  array $excludeFields = null) {
        return array_reduce($arrays, function ($carry, $array) use($excludeFields) {
            foreach ($array as $key => $value) {
                if (!isset($carry[$key])) {
                    $carry[$key] = 0;
                }else if ($excludeFields && !in_array($key, $excludeFields)) {
                    $carry[$key] += $value;
                } else {
                    $carry[$key] = $value;
                }
            }
            return $carry;
        }, []);
}

$arr = [
    ['a' => 1, 'b' => 3, 'c' => 5, 'd' => 7],
    ['a' => 2, 'b' => 4, 'c' => 6, 'd' => 8],
    ['a' => 3, 'b' => 7, 'c' => 11.03, 'd' => 15],
    ['a' => 6, 'b' => 14, 'c' => 22, 'd' => 30],
    ['a' => 12, 'b' => 28, 'c' => 44, 'd' => 60],
    ['a' => 24, 'b' => 56, 'c' => 88, 'd' => 120],
];

$sumArray = sumArrays($arr, ['a', 'b']);
print_r($sumArray);


echo '<br />';