简单的购物车程序

简单的购物车程序，用于练习，需求如下：

启动程序后，让用户输入工资，然后打印商品列表
允许用户根据商品编号购买商品
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
可随时退出，退出时，打印已购买商品和余额

#!/usr/bin/env python
#-*- coding:utf-8 -*-
# @Time    : 2017/9/14 16:46
# @Author  : lichuan
# @File    : shop_car.py

product_list={
    "lenove":3000,
    "ASUS":4500,
    "MSI":2800,
    "HP":4200
}
FLAG_TAG=True
count=0
shop_car = {}  # 已购物的商品
shop_list = []  # 购物车列表

while FLAG_TAG:
    salary=input("input 'q' to exit,please input your salary:")
    if salary == 'q':
        FLAG_TAG=False
    elif salary.isdigit():
        salary=int(salary)
    else:
        print("input wrong,try again!")
        continue
    for p in product_list:
        print("%d,%s  %d" % (count, p, product_list[p]))
        shop_list.append(p)
        count += 1

    while FLAG_TAG:
        product_num=input("input 'q' to exit,please input the product no:")
        if product_num == 'q':
            FLAG_TAG=False
        elif product_num.isdigit() and int(product_num) < count:
            product_num=int(product_num)
            if salary >= product_list[shop_list[product_num]]:
                if not shop_list[product_num] in shop_car:
                    shop_car[shop_list[product_num]]=1
                else:
                    shop_car[shop_list[product_num]]+=1
                salary = salary - product_list[shop_list[product_num]]
            else:
                print("余额不足：请选别的商品！")
                continue
        else:
            print("input 'q' to exit or input a number!")
            continue
        print("你购买的商品如下：")
        for s in shop_car:
            print("%s: %d" %(s,shop_car[s]))
        print("余额： %d" % salary)