delete array cookie and array cookie count as 1 cookie or more?

[searain]

I have been posted questions about array cookie and I searched my previous posts, not exactly the answers I was looking for. Here it is

1) If I saved the cookie in an array. like MyArray[0], MyArray[1], MyArray[3]. Is it one cookie or 3 cookies?

In the terms of the cookie limitation 20 per server. Some people suggest that I should use serilize to transfer MyArray to one string and save only one cookie.

But I think if I use the array, one array is one cookie not 3 cookies, am I right?

2) If I want to delete the cookie, now, such as sign out?

Do I have to use for loop to delete every element of the cookie array

for ($index=0; $index<count($MyArray); $index++)
{
setcookie("MyArray[$index])
}

or Can I just

setcookie("MyArray");