如何在php中计算总价格

我使用我存储在PHP数组中的产品ID从db获得产品的价格.

我有一个PHP功能,在我想要持有所有购买的产品.在这里,我得到购物车项目,我正在调用应该持有总金额的功能.每当我从购物车中取回产品时,我都会通过价值.

例如,对于第一项迭代,我发送值300,对于第二项400,对于第三项900.

我想将所有这些加在一起,并在paidamount()中获得1600的总价
我怎样才能做到这一点？

function getCartitems($product_id){
    $conn = new MysqLi(DB_HOST, DB_USER, DB_PASS, DB_NAME);
    if ($conn->connect_error) {
        die("Connection Failed: " . $conn->connect_error);
    } 
    $sql = "SELECT product_id,product_name,product_price,product_image_url FROM product_list WHERE product_id='$product_id'";
    $result = $conn->query($sql);      
    if ($result->num_rows > 0) {
        while($row = $result->fetch_assoc()) {              
        echo "<tr><td><img class='cart-image img-responsive' src='".$row["product_image_url"]."'></td><td>".$row["product_name"]."</td><td><b>&#8377; </b>".floor($row["product_price"])."</td><td><a href='mycart.PHP?action=remove&product_id=".$row['product_id']."'><span class='glyphicon glyphicon-remove'></span> remove</a></td></tr>";
        $price = $row['product_price'];
        payableAmount($price);      
        }
    } else {
        echo "There are no such items";
    }   
    $conn->close();
}

function payableAmount($totalPrice){    
   // calculate total price here
    $total = $totalPrice;
    echo $total;
}

解决方法:

您只需更新您的查询,而不是像

$total_price = 0;
while($row = $result->fetch_assoc()) {              
  echo "<tr><td><img class='cart-image img-responsive' src='".$row["product_image_url"]."'></td><td>".$row["product_name"]."</td><td><b>&#8377; </b>".floor($row["product_price"])."</td><td><a href='mycart.PHP?action=remove&product_id=".$row['product_id']."'><span class='glyphicon glyphicon-remove'></span> remove</a></td></tr>";
  $total_price += $row['product_price'];
}