python学习中需要住的问题1：注意条件的限制（列表的操作）

要求：
1、程序启动后，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、随时可以退出，退出时，打印已购买商品和余额

# -*- coding:utf-8 -*-
# Author :deng

product_list=[
    ('Iphone',5800),
    ('Mac Pro',9800),
    ('Bike',800),
    ('Watch',10800),
    ('Coffee',32),
    ('PthonCookBook',108),
]
# print(type(product_list[0][1]))
salary = input("Input your salary:")
if salary.isdigit():
    salary=int(salary)
    while  True:
        for item in product_list:
            print(product_list.index(item),item)
            #另一种方式 for index，item in enmerate（product_list）：
            #print（index，item）一次就返回所需要的值
        break
    while True:
        confirm = input('Exit:please input Q')
        if confirm == 'Q':
            break

        select_product = int(input('Select your product number:'))
        price  = product_list[select_product][1]
        if salary < price:
            print('Your money is not enough!')
            continue
        else:
            balance =salary - price
            print('Your balacne is:',balance)
        continue_confirm =input('Dou you want to buy anything?Y or N!')
        if continue_confirm != 'N':
            salary = balance
        else:
            print('谢谢光临！')
            break

备注： 在选择商品列表的时候 未考虑是否在商品列表内
　　　　在判断是否要退出的时候，太过于重复
　　　　最后一步没有写入程序中   

参考范例：

__author__ = "Alex Li"


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(product_list.index(item),item)
            print(index,item)
        user_choice = input("选择要买嘛？>>>:")
        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,your current balance is \033[31;1m%s\033[0m" %(p_item,salary) )
                else:
                    print("\033[41;1m你的余额只剩[%s]啦，还买个毛线\033[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")