python修行：练习购物车

product_list = [
    ('Iphone',5800),
    ('Mac Pro',9800),
    ('Bike',800),
    ('Watch',10600),
    ('Coffee',31),
    ('Alex Python',120)
]
shopping_list = []
salary = input("Input your salary:")
if salary.isdigit():
    salary = int(salary)
    while True:
        for index,item in enumerate(product_list):
            print(index,item)
            #print(product_list.index(item),item)

        user_choice = input("选择要选购的商品？>>>:")
        if user_choice.isdigit():
            user_choice = int(user_choice)
            if user_choice < len(product_list) and user_choice >= 0:
                p_item = product_list[user_choice]
                if p_item[1] <= salary: #买的起
                    shopping_list.append(p_item)
                    salary -= p_item[1]
                    print("Added %s into shopping cart,you current balance is 33[31;1m%s33[0m" %(p_item,salary))
                else:
                    print("33[41;1m你的余额只剩[%s]啦33[0m" % salary)
            else:
                print("product code [%s] is not exist!!" % user_choice)
        elif user_choice == "q":
            print("--------shopping list---------")
            for p in shopping_list:
                print(p)
            print("Your current balance :",salary)
            exit()
        else:
            print("invalid option")