我如何编写一个算法来使用 php $_SESSION 乘以购物车中的总*数量？

Question

I am writing a shopping cart and have my data stored in the $_SESSION array, but would like to calculate a total. below it the code I thought would work to do this, but it returns '1' in stead of a total!

$total = array($_SESSION['qty'],$_SESSION['pr']);

/* I'll give you more code...thanks for your help!! here is the code for my php cart:

<?php

function item_list() { if(isset($_SESSION['qty'])){ $total = array($_SESSION['qty'],$_SESSION['pr']);

    foreach($_SESSION['qty'] as $key => $value)
    {?>
        <tr>
    <td align="center"><?php echo $_SESSION['item'][$key]; ?></td>
    <td align="center"><?php echo $value; ?></td>
    <td align="center"><?php echo $_SESSION['pr'][$key]; ?></td>
    <td align="center"><?php echo array_product($total); ?>
    </tr><?php 
    }
}

}

session_start();

if(isset($_POST['clear']) && ($_POST['clear'] == 'clear')) { session_destroy(); unset($_SESSION['qty']); unset($_SESSION['item']); unset($_SESSION['pr']); unset($_POST['qty']); unset($_POST['item']); unset($_POST['pr']); }

if(!isset($_SESSION['qty'])) $_SESSION['qty'] = array(); if(!isset($_SESSION['item'])) $_SESSION['item'] = array(); if(!isset($_SESSION['pr'])) $_SESSION['pr'] = array();

if(isset($_POST['qty'])) {

foreach($_POST['qty'] as $value)
{
    if(!$value == '') array_push($_SESSION['qty'], filter_var($value, 

FILTER_SANITIZE_SPECIAL_CHARS)); } foreach($_POST['item'] as $key => $value) { if(!$_POST['qty'][$key] == '') array_push($_SESSION['item'], filter_var($value, FILTER_SANITIZE_SPECIAL_CHARS)); } foreach($_POST['pr'] as $key => $value) { if(!$_POST['qty'][$key] == '') array_push($_SESSION['pr'], filter_var($value, FILTER_SANITIZE_SPECIAL_CHARS)); }
}

?>

Answer 1

That is a strange way to structure a shopping cart, but here's how to do it with that structure:

foreach($_SESSION['qty'] as $key => $value)
{
    $total = $_SESSION['qty'][$key] * $_SESSION['pr'][$key];
?>
    <tr>
<td align="center"><?php echo $_SESSION['item'][$key]; ?></td>
<td align="center"><?php echo $value; ?></td>
<td align="center"><?php echo $_SESSION['pr'][$key]; ?></td>
<td align="center"><?php echo $total; ?>
</tr><?php 
}

If you wanted to get a total of all quantity and cost of the cart:

function getTotals()
{
    $total = array('qty' => 0, 'price' => 0);

    foreach($_SESSION['qty'] as $key => $qty)
    {
        $total['qty'] += $qty;
        $total['price'] += ($_SESSION['pr'][$key] * $qty)
    }

    return $total;
}

$total = getTotals();

echo $total['qty']; // output the total quantity of items
echo $total['price']; // output the total cost for all items and quantity

I would recommend a better structure though, something like:

$_SESSION['cart']['items'] = array(
    array(
        'name' => 'Screwdriver',
        'price' => 5,
        'qty' => 2,
    ),
    array(
        'name' => 'Hammer',
        'price' => 10,
        'qty' => 1,
    )
);

Answer 2

As per your cart array it is not able to hold multiple products you have to use multy dimensional array like this

$_SESSION['cart_items'] = array(
                array( "qty"=>5, "item"=>"tshirt", "pr"=>50.20), 
                array( "qty"=>2, "item"=>"Cell Phone", "pr"=>50.20),
                array( "qty"=>7, "item"=>"", "pr"=>50.20),      
               )

then you can write your code like this

function item_list()    
{

    foreach($_SESSION['cart_items'] as $item_array)
    {?>
        <tr>
    <td align="center">Item:<?php echo $item_array['item']; ?></td>
    <td align="center">Qty: <?php echo $item_array['qty']; ?></td>
    <td align="center">Price :<?php echo $item_array['pr']; ?></td>
    <td align="center">Total : <?php echo $item_array['qty'] * $item_array['pr']; ?>
    </tr><?php 
    }
}

Answer 3

You should create yourself a Card class that is able to import/export data from the $_SESSION superglobal (or some other array if you mock it for tests, testing with $_SESSION can be akward) which is able to handle your data-structure easily and can calculate the total, too:

$cart = new Cart();
$cart->importFromArray($_SESSION);
// or:
$cart->importFromArray($_SESSION['cart']);

// later on:
$total = $cart->getTotal();

// somewhere else:
$cart->addItem(...);
...
$_SESSION['cart'] = $cart->exportToArray();

That will allow you to more easily change the code over time.