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Currently im trying to create an ecommerce website by watching youtube videos. Now im at the stage where adding to cart is created. I have followed exactly as the code of the person who created the video. it worked for him but not for me. i have scanned my code with his a few times already and there wasnt any mistakes made such as wrong spelling, etc. I hope someone can guide me on this because i cannot proceed without accomplishing this stage.`function cart()

if(isset($_GET['add_cart']))

global $con;

$ip = getIp();

$pro_id = $_GET['add_cart'];

$check_pro = "select * from cart where ip_add='$ip' AND p_id='$pro_id'";

$run_check = mysqli_query ($con, $check_pro);

if(mysqli_num_rows($run_check)>0)

echo "";


else

$insert_pro = "insert into cart (p_id,ip_add) values ('$pro_id','$ip')";

$run_pro = mysqli_query($con, $insert_pro);

echo "<script>window.open('index.php','_self')</script>";

`

function getIp() 
$ip = $_SERVER['REMOTE_ADDR'];

if (!empty($_SERVER['HTTP_CLIENT_IP'])) 
 $ip = $_SERVER['HTTP_CLIENT_IP'];
 elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) 
 $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];


return $ip;

i have linked this functions in my homepage by using this code : <?php cart(); ?>