for实例

 #-*- coding:utf-8 *-*
 salary = 5000

 shop_list = [('iphone',9000),('mac book',10000),('python book',90),('coffee',32),
              ('bicycle',1500)]

 money = input("请输入您的现金总数：")
 money = int(money)
 have_buy_commodity = []
 while True:
     for i, v in enumerate(shop_list, 1):
         print(i, v)

     query_buy_shop = input("请输入要购买的商品编号，q[退出]：")

     if query_buy_shop.isdigit():
         query_buy_shop = int(query_buy_shop)

         if query_buy_shop >=1 and query_buy_shop <=5:
             spend_money = shop_list[query_buy_shop-1]
             buy_commodity = shop_list[query_buy_shop-1][0]
             money = money - spend_money[1]
             have_buy_commodity.append(buy_commodity)
             if money < 0:
                 print("您的余额不足！")
                 print('--------Shop List--------')
                 print(have_buy_commodity)
                 print('--------------------------')
                 break
             else:
                 print("您的余额为%s元!"%money)

         elif query_buy_shop == 'q':
             print("退出成功！")
             # print('--------Shop List--------')
             # print(have_buy_commodity)
             # print('--------------------------')

         else:
             print("输入的字符非法,请重新选择")