1 #Author:ersa
 2 ‘‘‘
 3 程序：购物车程序
 4 
 5 需求:
 6 
 7 启动程序后，让用户输入工资，然后打印商品列表
 8 允许用户根据商品编号购买商品
 9 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
10 可随时退出，退出时，打印已购买商品和余额
11 
12 #知识点：len(market):列表长度（列表中的条目个数）
13        isdigit() 判断输入的内容是否是数字，TRUE 是数字
14        取列表数据 enumerate
15        for index,item in enumerate(market)
16             print(index, item)
17     输出内容高亮显示 "\033[31;1m%s\033[0m"%(balance)
18     退出程序使用exit()方法
19 ‘‘‘
20 
21 market = [[1,"iphone",5800],
22           [2,"Mac Pro", 12000],
23           [3,"Starbuck Latte",31],
24           [4,"Alex Python",88],
25           [5,"bike",1800]]
26 
27 balance = input("please input salary: ")
28 if balance.isdigit():
29     balance = int(balance)
30 else:
31     exit("Illegal value, please re-enter")
32 
33 amount = 0
34 print("Tip: type q to exit.\n\n")
35 
36 shopping_cart = []
37 while True:
38     for commodity in market:
39         print(commodity)
40 
41     user_choice = input("Please enter a product number or q：\n")
42 
43     if user_choice == "q":
44         break
45 
46     if user_choice.isdigit():
47         user_choice = int(user_choice)
48         if 0 < user_choice and user_choice <= (len(market)+1):
49             amount += market[user_choice - 1][2];
50             if balance < amount:
51                 print("Reminder: the balance is insufficient, please re-purchase.\n")
52                 continue
53             shopping_cart.append(market[user_choice - 1])
54         else:
55             print("If you do not have this item, please reselect it !\n")
56             continue
57 
58 print("List of purchased items:\n")
59 for commodity in shopping_cart:
60     print(commodity)
61 print("Payment amount: \033[41;1m%s\033[0m"%(amount))
62 balance -= amount
63 print("your balance: \033[31;1m%s\033[0m \n"%balance)