php 加入购物车代码

<?php
session_start();

// 检查购物车是否存在，如果不存在则初始化为空数组
if (empty($_SESSION['cart'])) {
    $_SESSION['cart'] = [];
}

// 添加商品到购物车
function addToCart($productId, $quantity) {
    global $_SESSION;
    if (isset($_SESSION['cart'][$productId])) {
        $_SESSION['cart'][$productId] += $quantity;
    } else {
        $_SESSION['cart'][$productId] = $quantity;
    }
}

// 从购物车中移除商品
function removeFromCart($productId) {
    global $_SESSION;
    if (isset($_SESSION['cart'][$productId])) {
        unset($_SESSION['cart'][$productId]);
    }
}

// 显示购物车内容
function displayCart() {
    global $_SESSION;
    if (empty($_SESSION['cart'])) {
        echo "购物车为空";
    } else {
        foreach ($_SESSION['cart'] as $productId => $quantity) {
            echo "商品ID: $productId, 数量: $quantity<br>";
        }
    }
}

// 示例操作
if (isset($_GET['add'])) {
    $productId = $_GET['add'];
    addToCart($productId, 1);
}

if (isset($_GET['remove'])) {
    $productId = $_GET['remove'];
    removeFromCart($productId);
}

displayCart();
?>