Question

Here’s how it works. If a user clicks on the link to list the products then they will be directed to the products page. For security, I set something at the beginning to assure that either ‘cid’ or ‘sid’ is set. I am sure that the users are going to a page linked with cid or sid because it says it as I hover over it in my browser. Here’s the code

<?php require("includes/header.php"); ?>
<?php

if(!isset($_GET['cid'])||!isset($_GET['sid'])) {
    header("Location: index.php");
}

unfortunately, the users are still directed. I will post more of the code if necessary.

Answer 1

Your code requires that both $_GET['cid'] and $_GET['sid'] are defined, not that one of them is. Replace || with && in your condition.