title: PHP => $_SESSION Array only keeps last variable
body: <p>I'm building an interface for an online shop, where every item is a FORM and the BUY button is a submit,it submits the name and price of the clicked form and that data is displayed on a CONFIRM ORDER page. On that confirm order page I've created an array as follows</p>
  
  <pre><code>if (!isset($input_order_arr)) {
    $input_order_arr = array();
  }
  </code></pre>
  
  <p>After that I fetch the posted variables and push them into the array</p>
  
  <pre><code>if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    if (!empty($_POST['item-title'])  &amp;&amp; !empty($_POST['item-price'])) {
      $item_title = test_input($_POST['item-title']);
      $item_price = test_input($_POST['item-price']);
      array_push($input_order_arr,$item_title,$item_price);
    }
  }
  
  $_SESSION['chosen_item'] = $input_order_arr;
  </code></pre>
  
  <p><b>*NOTE</b> : test_input is a function that does striplashes , htmlspecialchars and htmltrim, for security purposes. (someone might edit the value of the item via the Chrome developer console? not sure if that holds any threat though)</p>
  
  <p>And after that the value is displayed in a table like so</p>
  
  <pre><code>              &lt;?php if (isset($_SESSION['chosen_item'])) {
                  foreach ($_SESSION['chosen_item'] as $value) {
                    echo "&lt;td&gt;" . $value . "&lt;/td&gt;";
                  }
                }  ?&gt;
  </code></pre>
  
  <p>And here comes the problem.</p>
  
  <p>If you order an item its price and name are displayed, but if u go back and you order another item, the previous item and its price are lost, as if its not adding new lines to the array,but replacing the old ones, or the session only saves data from one action, which wouldn't make any sense, since thats what $_SESSION is about, the code is presented with <code>session_start();</code> in every page that is using the $_SESSION variable.</p>
  
  <p><b> Main Question - Why could it be that the $_SESSION Array is losing its older inputs? </b></p>