数据结构：
goods = [
{"name": "电脑", "price": 1999},
{"name": "鼠标", "price": 10},
{"name": "游艇", "price": 20},
{"name": "美女", "price": 998},
]
功能要求：
基础要求：
1、启动程序后，输入用户名密码后，让用户输入工资，然后打印商品列表
2、允许用户根据商品编号购买商品
3、用户选择商品后，检测余额是否够，够就直接扣款，不够就提醒
4、可随时退出，退出时，打印已购买商品和余额
5、在用户使用过程中， 关键输出，如余额，商品已加入购物车等消息，需高亮显示
扩展需求：
1、用户下一次登录后，输入用户名密码，直接回到上次的状态，即上次消费的余额什么的还是那些，再次登录可继续购买
2、允许查询之前的消费记录

import os


def save(n, lst, udic, money, y):
    userdic['money'] = money
    n = n + 's'
    with open(n, 'w', encoding='utf-8') as f:
        lst[i - 1] = udic
        f.write(str(lst))
    os.remove(n.rstrip('s'))
    os.rename(n, n.rstrip('s'))


goods = [
    {"name": "电脑", "price": 1999},
    {"name": "鼠标", "price": 10},
    {"name": "游艇", "price": 20},
    {"name": "美女", "price": 998},
]
money = 0
car = []
userdic = {}
lst = []
i = 0
y = 0
f = open('user_message', 'r', encoding='utf-8')
sr = f.read()
if sr != '':
    lst = eval(sr)
while 1:
    name = input('请输入你的用户名:')
    password = input('请输入你的密码:')
    for n in lst:
        i += 1
        if n['name'] == name:
            money = int(n['money']) + int(money)
            userdic = n
            while 1:
                if n['password'] == password:
                    y = 1
                    break
                else:
                    password = input('密码错误,请重新输入:')
    if y == 1:
        print('登录成功')
        break
    g = input('帐号不存在,以此新建帐号输入Y,重新输入输入任意键:')
    if g.upper() == 'Y':
        userdic['name'] = name
        userdic['password'] = password
        userdic['money'] = money
        userdic['car'] = []
        lst.append(userdic)
        i = len(lst)
        break
while 1:
    money = input('请输入你的工资:')
    if money.isdigit():
        break
    print('工资输入错误,请重新输入')
f.close()
while 1:
    for n in range(len(goods)):
        print(n + 1, goods[n]['name'], goods[n]['price'])
    buy = input('请输入你需要的商品号.输入H显示消费记录,输入Q退出:')
    if buy == '':
        print('输入错误,请重新输入')
        continue
    elif buy.upper() == 'Q':
        print('你已经购买了:', userdic['car'], '\n你的余额为', money)
        save('user_message', lst, userdic, money, y)
        break
    elif buy.upper() == 'H':
        print('你购买了以下商品:')
        print(userdic['car'])
        print('请输入你需要的商品号.输入H显示消费记录,输入Q退出:')
    elif int(buy) == 1:
        if int(money) >= 1999:
            userdic['car'].append(goods[0]['name'].strip())
            money = int(money) - 1999
            save('user_message', lst, userdic, money, y)
            print('你购买了', goods[0]['name'], '余额', money)
        else:
            print('你的钱不够购买此商品:')
    elif int(buy) == 2:
        if int(money) >= 10:
            userdic['car'].append(goods[1]['name'].strip())
            money = int(money) - 10
            save('user_message', lst, userdic, money, y)
            print('你购买了', goods[1]['name'], '余额', money)
        else:
            print('你的钱不够购买此商品:')
    elif int(buy) == 3:
        if int(money) >= 20:
            userdic['car'].append(goods[2]['name'].strip())
            money = int(money) - 20
            save('user_message', lst, userdic, money, y)
            print('你购买了', goods[1]['name'], '余额', money)
        else:
            print('你的钱不够购买此商品:')
    elif int(buy) == 4:
        if int(money) >= 998:
            userdic['car'].append(goods[3]['name'].strip())
            money = int(money) - 998
            save('user_message', lst, userdic, money, y)
            print('你购买了', goods[1]['name'], '余额', money)
        else:
            print('你的钱不够购买此商品:')
    else:
        print('输入错误,请重新输入')