Product ID same, Quantity not increasing

[Tossyy]

When I add the product twice, it keep displaying in a new line, with new quantity. I want the quantity to update. here's the code:

<?
include "functions.php";
if(!$_SESSION['logged']){die();}
$_POST['taxes']=str_replace('undefined,','',$_POST['taxes']);
if(empty($_SESSION['products']))$_SESSION['products']=array();
 
    if($_POST['action']=='add'){
    $_POST[$qty]=str_replace(',','.',$_POST[$qty]);
        $_SESSION['products'][]=$_POST;
    }
    if($_POST['action']=='delete'){
        unset($_SESSION['products'][$_POST['id']]);
    }    
 
    if($_POST['action']=='update'){
        if($_POST['rule']==0)$_SESSION['products'][$_POST['id']]['qty']-=1;
        if($_POST['rule']==1)$_SESSION['products'][$_POST['id']]['qty']+=1;
    }
?>
 

[Dormilich]

I don’t think your posted code has anything to do with your problem.