Day2：购物车

需求：
1.启动程序后，让用户输入工资，然后打印商品列表；
2.允许用户根据商品编号购买商品；
3.用户选择商品后，检测余额是否足够，够就直接扣款，不够就提醒；
4.可随时退出，退出时打印已购买的商品列表。


# Author: Ewan Wang
shopping_list = []
goods_list = [
    (‘Nike shoes‘,800),
    (‘Mjstyle trousers‘,500),
    (‘Bag‘,300),
    (‘Dictionary‘,100),
    (‘Cup‘,80),
    (‘Skin lotion‘,60)
]
salary = input(‘Input your salary:‘)
if salary.isdigit():
    salary = int(salary)
    while True:
        for index,item in enumerate(goods_list):
         #print(goods_list.index(item),item)
          print(index,item)
        user_choice = input(‘The product you want to buy is‘)
        if user_choice.isdigit():
            user_choice = int(user_choice)
            if user_choice < len(goods_list) and user_choice >=0:
                p_item = goods_list[user_choice]
                if salary >= p_item[1]:
                    shopping_list.append(p_item)
                    salary -= p_item[1]
                    print(‘Add %s in your shopping cart,your salary balance is %s‘%(p_item[0],salary))
                else:
                    print(‘Your balance is insufficient.‘)
            else:
                print(‘Invalid option.‘)
        elif user_choice == ‘q‘:# 这里是==而非=
            print(‘----------shopping list---------‘)
            for p in shopping_list:
                print(p)
            exit()

Day2：购物车

原文：http://www.cnblogs.com/akonj3/p/7732636.html