将键添加到现有（或非）数组

I got this code:

if( empty ($cache[$id]) ) {
    $arr[$id] = @TIMENOW;
    setcookie('id', cArr($arr, 'set'), -1, @PATH);
} else {
    $cache[$id] = @TIMENOW;
    setcookie('id', cArr($cache, 'set'), -1, @PATH);
}

And it is adding only one key, to the cookie, if I'll go to the another thread , it'll reset the array, and won't add more keys. I mean, if the user goes to the thread with id 1 then if( empty ($cache[1]) ) is adding 1, instead it'll update existing value, AND if user will go now to the thread with ID 5, it will do the same, and if( empty ($cache[5]) ) is empty , then it'll add the key with ID 5 to the array so I'll have both keys now: 1 and 5.

Hope you got it. If you don't , feel free to ask for whatever you wan't, I'll reply for all of your quesitons.

It would be helpful to know what you're doing in cArr(). But without it, this will add to your cookie for each new thread a user visits.

//get previous values
$id = $_GET['thread_id'];
$cache = array_key_exists('id', $_COOKIE) ? unserialize($_COOKIE['id']) : array();

//add to $cache
$cache[$id] = TIMENOW;
setcookie('id', serialize(cArr($cache, 'set')), -1, PATH);

WARNING: But keep in mind, that with just setting a cookie, your webserver can be exploited. So better not use searialize and unserialize to store simple static values inside your cookie.