Insert cookie if value is not present - php

Question

I am trying to insert cookie. The logic is simple as:
Check if the value is present .
If not, insert new value with comma separated form.
I have tried some code but I could not able to get a correct result.
In this code a new value should be inserted, which is happening but not getting old value.
Edited Code 2
$current_value = '';
if(!isset($_COOKIE['blog_id_cookie'])){
setcookie('blog_id_cookie', $id);
$current_value[] = $_COOKIE['blog_id_cookie'];
} else {
$current_value = explode(',', $_COOKIE['blog_id_cookie']);
}
if(!in_array($id, $current_value)){
$current_value[] = $id;
$cookie_name = "blog_id_cookie";
setcookie($cookie_name, implode(',', $current_valu));
}

Answer 1

With that code $current_value will be defined only if the cookies is not set. Set $current_value in the else part. Concatenate the cookie instead of $current_value. Try with -
Update
$current_value = '';
if(!isset($_COOKIE['blog_id_cookie'])){
setcookie('blog_id_cookie', $id);
$current_value[] = $_COOKIE['blog_id_cookie'];
} else {
$current_value = explode(',', $_COOKIE['blog_id_cookie']);
}
if(!in_array($id, $current_value)){
$current_value[] = $id;
$cookie_name = "blog_id_cookie";
setcookie($cookie_name, implode(',', $current_value));
}