Go 语言代码简单的在线购物平台：

package main

import (
	"fmt"
)

type User struct {
	ID       int
	Name     string
	Email    string
	Password string
	Address  string
}

type Product struct {
	ID    int
	Name  string
	Price float64
}

type CartItem struct {
	Product Product
	Quantity int
}

type Order struct {
	ID         int
	User       User
	TotalPrice float64
	Items      []CartItem
}

type ShoppingPlatform struct {
	Users  map[int]User
	Products map[int]Product
	Orders map[int]Order
}

func main() {
	shoppingPlatform := ShoppingPlatform{
		Users:  make(map[int]User),
		Products: make(map[int]Product),
		Orders: make(map[int]Order),
	}

	// 添加一些用户
	shoppingPlatform.addUser(User{
		ID:       1,
		Name:     "John Smith",
		Email:    "john@example.com",
		Password: "password",
		Address:  "123 Main St",
	})
	shoppingPlatform.addUser(User{
		ID:       2,
		Name:     "Jane Doe",
		Email:    "jane@example.com",
		Password: "password",
		Address:  "456 Elm St",
	})

	// 添加一些产品
	shoppingPlatform.addProduct(Product{
		ID:    1,
		Name:  "iPhone 13",
		Price: 999.99,
	})
	shoppingPlatform.addProduct(Product{
		ID:    2,
		Name:  "Samsung Galaxy S21",
		Price: 899.99,
	})

	// 创建一个购物车
	cart := shoppingPlatform.createCart()

	// 向购物车中添加产品
	cart.addProduct(shoppingPlatform.Products[1], 2)
	cart.addProduct(shoppingPlatform.Products[2], 1)

	// 提交订单
	order := cart.checkout(shoppingPlatform.Users[1])
	shoppingPlatform.addOrder(order)

	// 显示用户的订单
	fmt.Printf("%s 的订单：\n", order.User.Name)
	for _, item := range order.Items {
		fmt.Printf("%s - 数量: %d, 单价: %.2f, 小计: %.2f\n", item.Product.Name, item.Quantity, item.Product.Price, item.Quantity*item.Product.Price)
	}
	fmt.Printf("总价格: %.2f\n", order.TotalPrice)
}

func (sp *ShoppingPlatform) addUser(user User) {
	sp.Users[user.ID] = user
}

func (sp *ShoppingPlatform) addProduct(product Product) {
	sp.Products[product.ID] = product
}

func (sp *ShoppingPlatform) createCart() Cart {
	return Cart{}
}

func (sp *ShoppingPlatform) addOrder(order Order) {
	sp.Orders[order.ID] = order
}

func (c *Cart) addProduct(product Product, quantity int) {
	item := CartItem{
		Product: product,
		Quantity: quantity,
	}
	c.Items = append(c.Items, item)
}

func (c *Cart) checkout(user User) Order {
	var totalPrice float64
	for _, item := range c.Items {
		totalPrice += item.Product.Price * float64(item.Quantity)
	}

	order := Order{
		ID:         len(shoppingPlatform.Orders) + 1,
		User:       user,
		TotalPrice: totalPrice,
		Items:      c.Items,
	}

	c.Items = []CartItem{} // 清空购物车

	return order
}