用Python编写购物车小程序

要求：

1.程序能对用户输入进行判断，不正确的输入会进行报错

2.用户能进行多次购买，退出程序时，输出用户余额，和所购买的商品

3.用户能够自己退出程序（输入特定字符，或者当用户余额不足时）

4.当用户输入金额时，界面自动弹出商品列表，并当用户再次购买时还会弹出商品列表

5.自主优化用户界面，进行友好的人机交互

# -*- coding:utf-8 -*-
things = [
    ('computer',4000),
    ('bike',800),
    ('phone',2000),
    ('python book',120),
    ('cup',8),
    ('coffer',30),
]
buy_things = []
salary = input('how much:')
if salary.isdigit():
    salary = int(salary)
    while True:
        print('------shopping things------')
        for index,item in enumerate(things):
            print(index,item)
        print('what do you want to buy?')
        what = input('>>>:')
        if what.isdigit():
            what = int(what)
            if what >= 0 and what < len(things):
                p_buy = things[what]
                if salary >= p_buy[1]:
                    salary -= p_buy[1]
                    buy_things.append(p_buy)
                    print('您购买商品%s花费%s,您的余额%s'%(p_buy[0],p_buy[1],salary))
                else:
                    print('您的余额不足！')
                    for i in buy_things:
                        print(i)
                    print('您的余额为%s'%salary)
                    exit()
        elif what == 'p':
            for i in buy_things:
                print(i)
            print('谢谢您的光临，您的余额为%s'%salary)
            exit()
        else:
            print('输入错误，请重新输入！')
else:
    print('您输入有误！')