根据之前看过的知识点，以自己的思路先写出了一个程序，后续继续老师的操作再进行优化。

 1 salary = int(input("请输入您的工资（单位 元）:"))
 2 
 3 print("以下是可购清单：")
 4 
 5 shopping_list = ['','iphone','computer','book','apple_juice','bread','cake']#商品列表
 6 commodity_prices = [0,6000,7000,2,3,3,5] #商品价格列表
 7 already_buy = []#已经购买的商品列表
 8 
 9 print("1.",shopping_list[1],commodity_prices[1],"元")
10 print("2.",shopping_list[2],commodity_prices[2],"元")
11 print("3.",shopping_list[3],commodity_prices[3],"元")
12 print("4.",shopping_list[4],commodity_prices[4],"元")
13 print("5.",shopping_list[5],commodity_prices[5],"元")
14 print("6.",shopping_list[6],commodity_prices[6],"元")
15 
16 select = ""
17 while select != "quit":
18     select = input("购买您需要的宝贝至购物车，请输入数字（如需结算，输入 quit）：")
19     print()
20     if select == "1":
21         salary = salary - commodity_prices[1]
22         if salary < 0:
23             print("余额不足，",salary)
24             salary = salary + commodity_prices[1]
25         else:
26             print("已加入",shopping_list[1],"到你的购物车，当前余额：",salary)
27         already_buy.append(shopping_list[1])
28     elif select == "2":
29         salary = salary - commodity_prices[2]
30         if salary < 0:
31             print("余额不足，", salary)
32             salary = salary + commodity_prices[2]
33         else:
34             print("已加入", shopping_list[2], "到你的购物车，当前余额：", salary)
35         already_buy.append(shopping_list[2])
36     elif select == "3":
37         salary = salary - commodity_prices[3]
38         if salary < 0:
39             print("余额不足，", salary)
40             salary = salary + commodity_prices[3]
41         else:
42             print("已加入", shopping_list[3], "到你的购物车，当前余额：", salary)
43         already_buy.append(shopping_list[3])
44     elif select == "4":
45         salary = salary - commodity_prices[4]
46         if salary < 0:
47             print("余额不足，", salary)
48             salary = salary + commodity_prices[4]
49         else:
50             print("已加入", shopping_list[4], "到你的购物车，当前余额：", salary)
51         already_buy.append(shopping_list[4])
52     elif select == "5":
53         salary = salary - commodity_prices[5]
54         if salary < 0:
55             print("余额不足，", salary)
56             salary = salary + commodity_prices[5]
57         else:
58             print("已加入", shopping_list[5], "到你的购物车，当前余额：", salary)
59         already_buy.append(shopping_list[5])
60     elif select == "6":
61         salary = salary - commodity_prices[6]
62         if salary < 0:
63             print("余额不足，", salary)
64             salary = salary + commodity_prices[6]
65         else:
66             print("已加入", shopping_list[6], "到你的购物车，当前余额：", salary)
67         already_buy.append(shopping_list[6])
68 else:
69     print("您已购买以下商品：")
70     print(already_buy)
71     print("余额为：",salary)
72     print("谢谢惠顾，欢迎下次光临！")
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2019.5.20 根据老师讲课的内容进行优化

知识点1：列表的值可以进行嵌套。 如 sale_list = [['iphone',6000],('book',500),500,'bike'] 列表里面的值可以是 列表、元组、数字、字符串等

知识点2：嵌套列表取值， sale_list[0][1] 返回值是:6000

知识点3：函数 enumerate(sale_list,1) 。 在列表“sale_list”前面自动打印序号，默认不写“1”就从“0”开始

知识点4：for sale,price,unit in sale_list:。  通过for循环，把列表中的值取出来。

知识点5：print("已购买%s,当前余额：%d" % (sale_list[select - 1][0], saving))。 定位符使用

知识点6：函数 len(product_list)。 算出列表的长度

 1 # 商品列表
 2 sale_list = [
 3     ['iphone',7000,"￥"],
 4     ['bike',600,"￥"],
 5     ['computer',8000,"￥"],
 6     ['pen',3,"￥"],
 7     ['book',2,"￥"],
 8     ['desk',500,"￥"]
 9 ]
10 
11 # 已购商品列表
12 shopping_list = []
13 
14 # 预存金额，让用户自己输入
15 saving = input("请输入您需要存储的金额：")
16 # 判断是否输入的为数字
17 if saving.isdigit():
18     saving = int(saving)
19 else:
20     print("请输入数字！！！")
21 
22 # 用while实现用户一直购物
23 while True:
24 
25     # for number,list in enumerate(sale_list,1):  #展示商品列表,此老师方法展示不好看，自己想了另外一个表达方式
26     #     print(number,"  ",list)
27     number = 0
28     for sale,price,unit in sale_list:
29         number += 1
30         print("商品代码:",number,"  ",sale,price,unit)
31 
32     select = input("请输入您要购买的商品代码（退出，按‘Q’）：")  #让用户选择购买的商品
33     if select.isdigit():
34         select = int(select)
35         if saving >= sale_list[select - 1][1]:  #判断是否买得起
36             shopping_list.append(sale_list[select - 1]) #将购买的商品加入已购清单
37             saving -= sale_list[select - 1][1]  #算出余额
38             print("已购买%s,当前余额：%d" % (sale_list[select - 1][0], saving))
39         else:
40             print("余额不足，还剩余额为：%d" % saving)
41     elif select == "q" or select == "Q":    #结算清单
42         print("--------------您购买的清单如下-----------------")
43         for shopping,price,unit in shopping_list: #打印已购清单
44             print(shopping,price,unit)
45         print("------------------------------------------------")
46         print("welcome to you again!!!")
47         break
48     else:
49         print("输入有误，请重新正确输入")
View Code