Python 元组

1 '''
2 练习
3 需求:
4 1. 启动程序后,让用户输入工资,然后打印商品列表
5 2. 允许用户根据商品编号购买商品
6 3. 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
7 4. 可随时退出, 退出时,打印已购买商品和余额
8 
9 
10 分析:
11 1. 让用户输入salary
12 2. 商品列表
13 3. 开始让用户购买, for 循环, 已购买商品加入已购买商品列表
14 a. 输入商品名, salary和价格相比, 大于则可以购买,并添加已购买商品列表;小于则返回购买力不足.
15 b. 上述进程加入循环中. 并确定退出标志.
16 5. 循环结束后,打印已购买商品列表
17 
18 Note:上述方法暂时无法实现, 因为list没法像Java的list一样,有key/value组合, 无法根据key去匹配.所以暂时通过索引让用户去选择商品而不是商品名.
19 '''
20 
21 ''''
22 prod_list = [
23 ("iphone", 5000),
24 ("Mac Pro", 12000),
25 ("Starbuck", 31),
26 ("alex", 81),
27 ("Bike", 800)]
28 
29 shopping_list = []
30 
31 salary = input("salary: ")
32 if salary.isdigit():
33 salary = int(salary)
34 while True:
35 
36 取得商品及其索引 方法1: 
37 for item in prod_list:
38 print(prod_list.index(item),item)
39 break
40             
41 方法2:
42 for index, item in enumerate(prod_list)
43 print(index, item)
44 break
45      
46 for index, item in enumerate(prod_list):
47 print(index, item)
48 
49 user_choice = input("选择要买的商品: ")
50 if user_choice == "quit":
51 print("已购买商品清单:", shopping_list)
52 break
53 else:
54 if user_choice.isdigit():
55 user_choice = int(user_choice)
56 if (user_choice <= len(prod_list) - 1) & (user_choice >= 0):
57 p_item = prod_list[user_choice]
58 if salary >= p_item[1]:
59 shopping_list.append(p_item)
60 salary = salary - p_item[1]
61 print("已购买商品清单:", shopping_list)
62 print("========================")
63 else:
64 print("余额不足")
65 else:
66 print("商品不存在")
67 else:
68 print("请选择商品")
69 
70 '''
71 
72 
73 prod_list =[
74     ("iphone", 5000),
75     ("Mac Pro", 12000),
76     ("Starbuck", 31),
77     ("alex", 81),
78     ("Bike", 800)]
79 
80 shopping_list =[]
81 
82 salary = input("salary: ")
83 ifsalary.isdigit():
84     salary =int(salary)
85     whileTrue:
86         for index, item inenumerate(prod_list):
87             print(index,item)
88 
89         user_choice = input("要买什么? ")
90         ifuser_choice.isdigit():
91             user_choice =int(user_choice)
92             if len(prod_list) > user_choice >=0:
93                 p_item =prod_list[user_choice]
94                 if salary>=p_item[1]:  #买得起
95 shopping_list.append(p_item)
96                     salary-=p_item[1]
97                     print("Added %s into shopping cart, your current balance is