我们如何在php中为现有cookie添加cookie值

this my code but i am not getting the my cookie value in page

if (isset($_COOKIE['mycookie'])) {

    $cookie[] = $proID;
    $cookie = implode(',', $cookie);
    $cookie = unserialize($cookie);
    setcookie('mycookie', serialize($cookie), time() + (86400 * 30), '/');

}

You are doing isset($_COOKIE['mycookie']) which will check if the $_COOKIE['mycookie'] is set or not, will return true if set else false. And if you are setting it inside the if block for the first time it will never be set. So it should be -

if(!isset($_COOKIE['mycookie']))
    // Set the cookie   
}

First get the old value of the cookie, and turn it into an array with unserialize. If the cookie isn't set, initialize it to an empty array.

if (isset($_COOKIE['mycookie'])) {
    $cookie = unserialize($_COOKIE['mycookie']);
} else {
    $cookie = array();
}

Then add the new element to the array, and save it back into the cookie.

$cookie[] = $proID;
setcookie('mycookie', serialize($cookie), time() + (86400 * 30), '/');