在PHP中使用键比较两个数组，并根据键减去值

$array1 = array('a' => 1, 'b' => 2, 'c' => 3);
$array2 = array('a' => 4, 'b' => 5, 'd' => 6);

$result = array_diff_key($array1, $array2);

print_r($result);

Array
(
    [c] => 3
)

$array1 = array('a' => 1, 'b' => 2, 'c' => 3);
$array2 = array('a' => 4, 'b' => 5, 'd' => 6);

foreach ($array1 as $key => $value) {
    if (isset($array2[$key])) {
        $array1[$key] -= $array2[$key];
    }
}

print_r($array1);

Array
(
    [a] => -3
    [b] => -3
    [c] => 3
)