作业二：优化购物车：用户入口：1.将商品的信息存到文件中；2.将已经购买的商品、余额记录存到文件中。商家入口：1.可以添加商品；2.可以修改商品的价格

#Author:AXIN
#Date:2017/5/22 12:04
#优化版的购物车
#用户入口：
#1.商品的信息存到文件里
#2.已购商品，余额记录
#商家入口：
#1.可以添加商品
#2.修改商品价格
product_list = [
    (‘Iphone‘,5288),
    (‘Mac pro‘,12000),
    (‘Bike‘,800),
    (‘Watch‘,36000),
    (‘Coffe‘,39),
    (‘Python book‘,120),
]
#将商品信息打印到console窗口下
def print_write_product():
    print_list()
    # 将商品信息写入product.txt文件
    f = open("product.txt", ‘w‘)
    f.write(str(product_list) + "\n")
    f.close()
#用户输入自己的薪水
def choose_product():
    salary = input("Please input your salary :")
    if salary.isdigit():
        salary = int(salary)
    #用户选择要购买的商品
    shopping_list = []
    while True:
        user_choice = input(‘Please input your wanna product number :‘)
        if user_choice.isdigit():
            user_choice = int(user_choice)
            if user_choice >=0 and user_choice <= len(product_list):
                p_item = product_list[user_choice]
                if salary >=  p_item[1]:
                    shopping_list.append(p_item)
                    salary -= p_item[1]
                    print("Added %s into shopping cart,your current balance is %s " % (p_item, salary))
                else:
                    print(‘Your salary is not enough !Your balabce only [%s] !‘%salary)
            else:
                print("Product code [%s] is not exist !" % user_choice)
        elif user_choice ==‘q‘:
            f = open("shopping_record.txt", ‘w‘)
            print(‘--------------shopping_list---------------‘)
            for p in shopping_list:  # python 中直接使用的变量初始化的 就是0，不用定义再使用
                print(p)
                f.write(str(p) + "\n")
            f.write(str(salary) + "\n")
            print(‘Your balance :‘, salary)
            f.close()
            print(‘exit....‘)
            exit()
        else:
            print(‘Invalide choice ‘)
#专门给商家提供的入口：
#增加货物
def add_product(tuple):
    product_list.append(tuple)
    print_list()
#修改价格
def modify_price(i):
    print(‘Input the changed product and price:‘)
    product_list[i] = input(tuple)
    print_list()
#请用户输入自己是商家还是用户
def identity():
    i = input(‘business-----b‘‘\n‘
              ‘client-------c‘‘\n‘)
    return i
#商家可执行菜单选项
def select_service():
    i = input(‘adding goods-----a‘‘\n‘
              ‘change the price of the product-------c‘‘\n‘)
    return i
def print_list():
    for index, item in enumerate(product_list):  # enumerate 能把下标取出来
        print(index, item)
#主函数

i = identity()
if i == ‘b‘:
    j = select_service()
    if j == ‘a‘:
        print_list()
        a = input(‘Input adding product and price:‘)
        add_product(a)
        f = open("c_product.txt", ‘w‘)
        f.write(str(product_list) + "\n")
        f.close()
    elif j == ‘c‘:
        print_list()
        c = int(input(‘Input what you wanna changed number:‘))
        modify_price(c)
        f = open("c_product.txt", ‘w‘)
        f.write(str(product_list) + "\n")
        f.close()
elif i == ‘c‘:
    print_write_product()
    choose_product()
else:
    print(‘Invalied input !‘)