购物车完善版，客户余额及所购商品保存在文件

购物车优化：
用户入口：
商品信息存在文件里；
已购商品，余额记录保存在文件里，下次运行程序要读取上一次运行后的余额信息
商家入口：
可以添加商品，修改商品价格

文件：
1. customer.txt
3220
{'shampoo': '1', 'iphone 8': 2, 'iphone X': 2, 'starbucks latte': 6, 'bread': 13, 'book': 12, 'MacPro': 1}

2. goods.txt
{"MacPro":"12000","iphone 8":"8000","iphone X":"10000","starbucks latte":"25","book":"50","bread":"5","shampoo":"25"}

3. index.py

 

import json
with open("goods.txt",'r') as f:
   contents = f.read()
goods_list = json.loads(contents)   # convert to dict type 获取商品列表，字典格式
with open("customer.txt",'r') as f:
   contents = f.readlines()
customer_lines = list()
for line in contents:
    customer_lines.append(line.strip())
salary = int(customer_lines[0])         # 分别获取余额和已购买的商品
items_bought = eval(customer_lines[1])    # 字符串转换成字典

confirm = input("Your balance is {balance}, do you want to add more money? 'y' to add".format(balance = salary))   # 要不要加钱
if confirm == 'y':
    add_salary = int(input("Money you wanna add: "))
    salary = salary + add_salary                # 更新余额
    print("Your latest balance is {salary}".format(salary = salary))

available_goods = list()    # available_goods 保存的是根据salary可以买的商品
for i in goods_list:
    if salary >= int(goods_list[i]):
        available_goods.append(i)
if len(available_goods) == 0:
    print("You have no enought money, now exit.")       # 没有可以购买的商品，直接退出
    exit()
print("Goods for you:")
goods_order = 1
for j in available_goods:       # 一行一个打印出可以购买的商品
    print("{goods_order}: {j}, price: {goods}".format(goods_order=goods_order,j=j, goods=goods_list[j]))
    goods_order += 1
# print(len(available_goods))   # 有多少个商品可以买

chose_list = dict()
total_price = 0
total_price_tmp = 0
while True:
    choose_order = int(input("Please choose an item:"))
    while choose_order > len(available_goods) or choose_order <= 0:      # 如果可购买商品列表范围，则提示用户直到输入的order存在为止
        choose_order = int(input("The item you selected not exsit, try again:"))
    choose_order_num = int(input("How many do you want?"))
    if available_goods[choose_order-1] in chose_list:
        chose_list[available_goods[choose_order - 1]] = chose_list[available_goods[choose_order-1]] + choose_order_num
    else:
        chose_list[available_goods[choose_order-1]] = choose_order_num
    print("Items you chose:")
    for i in chose_list:                # 打印出本次选择的商品及数量
        print(i,':',chose_list[i])
    for k in chose_list:                # 计算本次选购商品的总价格
        total_price_tmp = total_price_tmp + int(goods_list[k])*chose_list[k]
    total_price = total_price_tmp
    total_price_tmp = 0
    if salary < total_price:            # 如果超过余额，则清空重选
        print("The total price of your items is {total_price}".format(total_price=total_price))
        print("You don't have enought balance. please try again.")
        chose_list.clear()
        total_price = 0
    else:
        print("The total price of your items is {total_price}".format(total_price=total_price))
    buy_again = input("'c'to calculate, 'q' to cancel, other key to continue:")         # 继续不
    if buy_again == "q":
        print("Cancel all. Your balance is {salary}".format(salary=salary))
        break
    elif buy_again == 'c':              # 选c 计算商品价格
        balance = salary - total_price
        if balance == salary:
            print("Your balance is {balance}, you didn't buy anything.".format(balance=balance))
        else:
            print("Your balance is {balance}, the items you bought this time are blow:".format(balance=balance))
        for item in chose_list:
            print("{item}, amount: {count}, cost {price}".format(item = item, count = chose_list[item], price = int(chose_list[item]) * int(goods_list[item])))
        break
for i in chose_list:        # 更新购买的商品字典
    if i in items_bought:
        items_bought[i] += chose_list[i]
    else:
        items_bought.update(chose_list)
print("All the items you bought are blow:")
for i in items_bought:
    print(i,':',items_bought[i])
f = open("customer.txt","w")        # 更新customer.txt文件
f.write(str(balance)+'\r')
f.write(str(items_bought))
f.close()