What is the purpose of the PHP code in the addtocart.php file?

The purpose of the PHP code in the addtocart.php file is to handle the functionality of adding items to the shopping cart. This code typically receives data from a form submission, processes the data, and updates the cart accordingly. 

<?php
// Start session to access session variables
session_start();

// Check if product ID is provided
if(isset($_POST['product_id'])) {
    $product_id = $_POST['product_id'];

    // Add product to cart or update quantity
    if(isset($_SESSION['cart'][$product_id])) {
        $_SESSION['cart'][$product_id]['quantity']++;
    } else {
        $_SESSION['cart'][$product_id] = array('quantity' => 1);
    }

    // Redirect back to the product page
    header('Location: product.php?id=' . $product_id);
    exit;
}
?>

Keywords

PHP addtocart.php e-commerce shopping cart functionality

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