购物车小程序客户端

要求：

　　1.用户输入金额后，就可以选择商品添加进购物车

　　2.金额不足扣款时，提示用户余额不足

　　3.当用户随时可以退出程序

　　4.退出程序后自动保存金额和所购商品

# -*- coding:utf-8 -*-
import time
#分别打开商品列表的储存文件和余额列表的储存文件
with open ('ware_list','r',encoding = 'utf-8')as ware:
    ware = eval(ware.read())
with open ('balance','r+',encoding = 'utf-8') as balance:
    balance = eval(balance.read())

shopping_cart = []
warelist = []
#根据商品数量打印商品列表
def ware_list():
    print('---------商品列表-----------')
    count = 0
    for i in ware:
        count += 1
        print(count,'.',i,'    ',ware[i])
        if i in warelist:
            continue
        else:
            warelist.append(i)
def timmer():
    time.format ='%Y-%m-%d %X'
    time.current = time.strft(time.format)
    print(time.current)

#判断是否有余额文件如果有则将余额值赋予工资变量
if balance['balance'] > 0:
    print(('well come back! ur balance :{0} ur bought list :{1}').format(balance['balance'],balance['shopping cart']))
    shopping_cart.extend(balance['shopping cart'])
    salary = balance['balance']
else:
    salary = input('请输入您的工资：')
while True:
    salary = int(salary)
    ware_list()
    choice = input('你想购买什么商品？\n (输入Q退出)')
        #如果输入为q则可以退出
    if choice.upper() == 'Q':
        request = input('请确认是否退出？Y/N')
        #
        if request.upper() ==  'Y':
            break
        elif request.upper()== 'N':
            continue
        else:
            print('非法输入！！')
            continue
    elif len(choice)<= len(warelist):
        if salary - int(ware[warelist[int(choice)-1]]) > 0:
            shopping_cart.append(warelist[int(choice)-1])
            salary -= int(ware[warelist[int(choice)-1]])
            print(('您已经购买：{0} 余额为：{1}').format(shopping_cart,salary))
            time.format ='%Y-%m-%d %X'
            time.current = time.strftime(time.format)
            print(time.current)

        else:
            print('您的余额不足购买该商品 请重新选择')

    else:
        print('请正确输入商品序号！')
        continue

#保存余额信息
print(('您一共购买了{0}件商品，您的余额剩余：{1} 购买了：{2}').format(len(shopping_cart),salary,shopping_cart))
with open("balance",'w',encoding='utf-8')as new:
    new.write("{'balance':%d,'shopping cart':%s}"%(salary,shopping_cart))

缺陷：无法针对回车等非法输入进行限制

思路：因为要求随时可以退出程序  所以减少循环层数是减少工作量提高代码运行效率的最好方式  所以我就只用了一个主循环