php比较两个关联数组

$a = array('a' => 1, 'b' => 2, 'c' => 3);
$b = array('b' => 2, 'c' => 4, 'd' => 5);
$diff = array_diff($a, $b);
print_r($diff);

Array
(
    [1] => 1
    [2] => 3
)

$a = array('a' => 1, 'b' => 2, 'c' => 3);
$b = array('b' => 2, 'c' => 4, 'd' => 5);
$intersection = array_intersect($a, $b);
print_r($intersection);

Array
(
    [b] => 2
    [c] => 3
)

$a = array('a' => 1, 'b' => 2, 'c' => 3);
$b = array('b' => 2, 'c' => 4, 'd' => 5);
$keys_a = array_keys($a);
$keys_b = array_keys($b);
$keys_diff = array_diff($keys_a, $keys_b);
print_r($keys_diff);

Array
(
    [1] => a
    [2] => c
)