PHP添加到购物车会话错误

Question

I'm testing out this simple shopping cart code and for some reason it doesn't seem to work. I've created 3 pages, 1st page contains:

<a href="add-to-cart.php?id=1">Item 1</a><br><br>
<a href="add-to-cart.php?id=2">Item 2</a><br><br>
<a href="add-to-cart.php?id=3">Item 3</a><br><br>

On the 2nd (add-to-cart.php) page:

<?php
session_start();

if(empty($_session['cart'])){
$_session['cart'] = array();
}

array_push($_session['cart'], $_GET['id']);
?>
<br><br>
Product is succesfully added to cart.
<a href="cart.php">View Cart Items</a>

Finally, on the 3rd (cart.php) page:

<?php 
session_start();

var_dump($_session['cart']);
?>

Instead of array, i get this error:

Notice: Undefined variable: _session in C:\xampp\htdocs\projects\add_to_cart\independent\compare.php on line 4

NULL

Answer 1

You have to write session in capital letters like:

$_SESSION["cart"] 

and not:

$_session["cart"]  //if you write it like this it's a normal array

So your code should look like this:

add-to-cart.php:

<?php
session_start();

if(empty($_SESSION['cart'])){
$_SESSION['cart'] = array();
}

array_push($_SESSION['cart'], $_GET['id']);
?>
<br><br>
Product is succesfully added to cart.
<a href="cart.php">View Cart Items</a>

cart.php:

<?php 

    session_start();
    var_dump($_SESSION['cart']);

?>

For more information see: http://php.net/manual/en/reserved.variables.session.php