$array
=
[
'red' => 2,
'purple' => 4,
]
#1
|
array_diff_ukey
|
(["blue" => 1, "red" => 2, "green" => 3, "purple" => 4], |
#2
|
array_diff_ukey
|
([0 => "a", 1 => "c"], |