从多重数组的特定元素求和

我正试图在我的可变会话篮中获得一个和（它是一个多数组），我想对表示产品成本的元素求和。

Page where I add elements into the basket
<?php
   session_start();
   include('link.php');
  
   if(!isset($_SESSION['basket'])){
   	$_SESSION['basket']=[];
   }
   // $id_permit=$_POST['id_fp'];
   // $chosen_date=$_POST['date_permit'];
 
  
   $_SESSION['little_basket']= array (
   'itemIdPermit'=> "'".$_POST["id_fp"]."'",
   'itemChosenDate'=> "'".$_POST["date_permit"]."'",
   'itemFinalPrice'=> "'".$_POST["final_price"]."'",
   'itemFinalPriceNotDiscount'=>"'".$_POST["price_not_discount"]."'"
                                                        );
                                    
  // $_SESSION['basket'][] = $_SESSION['little_basket'];
  
   array_push($_SESSION['basket'], $_SESSION['little_basket']);
   print_r($_SESSION['basket']);
   // $_SESSION['basket']=[];
   // echo $_SESSION['basket'];
    // header('location:index.php?area=fishing_permit');
   
   
?>
Page where I show the contents of the basket
<?php
  // session_start();
  // include('link.php');
   // include('add_basket.php');
  // $ids = '';
   /* foreach($_SESSION['basket'] as $id){
    $ids = $ids . $id . ",";
    };*/
    $lista_de_items_no_carrinho = $_SESSION['basket'];

  
    ?>
    <ul id="list_product">
     
    <?php
  
     $basketLength=count($lista_de_items_no_carrinho);
    for($i=0;$i< $basketLength;$i++){
   $sqlListChosenPermits = "select * from type_of_permits
   where id_type_of_permit =".$lista_de_items_no_carrinho[$i]['itemIdPermit'];
   $outcomeListChosenPermits = $link->query($sqlListChosenPermits);
   $line = mysqli_fetch_assoc($outcomeListChosenPermits);
   ?>
    <li>
      <div class="box_info"><h4><?php echo utf8_encode($line['type']); ?></h4><br>Validity:&nbsp;<?php echo utf8_encode($line['validity']);?>&nbsp;-&nbsp;Price:&nbsp;€<?php echo utf8_encode($line['price_eur']); ?> </div>
        
            <div class="map">Map info</div>
               <div class="rules">Rules</div>
         
                <div class="permit_facsimile"><a href="<?php echo $line['map']; ?>">Permit facsimile</a></div>
                <div class="chosen_date"><?php echo trim ($lista_de_items_no_carrinho[$i]['itemChosenDate'], "'") ;?></div>
        <div class="price">Euro&nbsp;<?php 
        $var= trim ($lista_de_items_no_carrinho[$i]['itemFinalPrice'],"'");
        if (!empty($var) ){
          
          echo  ($var);
        } else {
          echo trim($lista_de_items_no_carrinho[$i]['itemFinalPriceNotDiscount'],"'");
          } ?></div>
    
        <div class="add_basket"><a href="remove_from_basket.php?id=<?php echo $lista_de_items_no_carrinho[$i]['itemIdPermit']?>"><i class="fa fa-shopping-cart"></i>Remove from the Basket</a></div>
        <input type="hidden" name="last_price" id="last_price" value="<?php 
  
        if (!empty($lista_de_items_no_carrinho[$i]['itemFinalPrice'])) {
          
          echo trim ($lista_de_items_no_carrinho[$i]['itemFinalPrice'],"'");
        } else {
          echo trim($lista_de_items_no_carrinho[$i]['itemFinalPriceNotDiscount'],"'");
          } ?>">
     </li>
     <?php
    }
?>
    
    </ul>
<p>Total price:<span class="total_price"><?php
$lista_de_items_no_carrinho = $_SESSION['basket'];
$listaPrice=$lista_de_items_no_carrinho[$i]['itemFinalPriceNotDiscount'];
 $basketLength=count($listaPrice);
 $sum=0;
for($k= 0; $k < $basketLength; $k++){
$sum += ($basketLength[$k]);
echo ($sum);
}?>
 </span></p>
    
   <div class="buying"><button type="submit"><i class="fa fa-shopping-cart"></i>Conclude the purchase</button></div>
   
</div>

我想求和"ItemFinalPrice"answers"ItemFinalPriceNotDiscount"的数值。

提前谢谢。

Fanjo