[1.6] Total sum of products quantity

[ReinH]

Hi,

Let's consider the following. The attached picture is the following foreach loop:
 

        {foreach from=$order_products item=product}
            <tr>
                <td class="custom-td">{$product.product_name}</td>
                <td class="custom-td-price">
                    {if $use_taxes}
                        {displayPrice price=$product.total_price_tax_incl}
                    {else}
                        {displayPrice price=$product.total_price_tax_excl}
                    {/if}
                </td>
                <td class="custom-td-qty">{$product.product_quantity}</td>
            </tr>
        {/foreach}

Which is taken from the following tutorial: http://nemops.com/prestashop-order-confirmation-resume/

I've been trying to make a sum of the total quantity of the cart in question to populate the variables of a javascript tracker, but I've got no idea on how to make that.
I've tried to call $cart_qties to get the whole total of the order, but it will show just 0. 

I don't have much experience with smarty, but How can I achieve the thing that I need? It's a simple sum of the output of the foreach loop.
2+3+3+2

Edited March 2, 2019 by ReinH (see edit history)

[ReinH]

Well, nevermind. I'm not sure if this is the right way, but if anyone needs it this is how I made it:
 

    {foreach from=$order_products item=product}
        {$product.product_quantity}
        {assign var="sum_elements" value=$sum_elements+$product.product_quantity}
    {/foreach}
    = {$sum_elements}

Pretty simple, I can't believe I spent 3 hours doing this.