python实现简单的购物车

salary = input('input your salary:')if salary.isdigit:    salary = int(salary)else:    exit('salary is not digit!!')welcome_msg = 'welcome to our shoping mall'print(welcome_msg.center(50,'-'))  #.center（距离，字符）还挺好玩product_list = [    ('Iphone',5888),    ('Mac Air',8000),    ('XiaoMi',19.9),    ('coffee',30),    ('Tesla',820000),    ('Bike',700),    ('Cloth',200)]#定义购物车一个空列表shop_car = []#标志位exit_flag = 0while exit_flag is not True:    print('product list :'.center(50,'-'))    for item in enumerate(product_list):  #实现更加优美的索引        #print(item) item实际上是(0, ('Iphone', 5888))这个模样了，下面把它拆分了        index = item[0]     #获得商品序号        p_name = item[1][0]   #获得商品名称        p_price= item[1][1]   #获得商品价格        print(index,p_name,p_price)    user_choice = input('[q=quit,c=check]  what do you want to buy?:')    if user_choice.isdigit():        user_choice = int(user_choice)        if user_choice < len(product_list):  #输入的商品序号要在范围之内            p_item = product_list[user_choice] #选择的商品            if p_item[1] <= salary:  #买得起                shop_car.append(p_item)  #放入购物车                salary -= p_item[1]  #减钱                print('purchased products are:'.center(40, '-'))                for item in shop_car:                    print(item)                print('Your balance is [%s]' % salary)            else:                   #买不起                print('Your balance is [%s],cannot buy the product!'%salary)        else:            print('we do not have the product,please input again!')    elif user_choice == 'q' or user_choice == 'quit':        print('purchased products are:'.center(40,'-'))        for item in shop_car:            print(item)        print('END '.center(40,'-'))        print('Your balance is [%s]'%salary)        exit_flag =True    elif user_choice == 'c' or user_choice == 'check':        print('purchased products are:'.center(40, '-'))        for item in shop_car:            print(item)        print('Your balance is %d' % salary)        print('Check '.center(40, '-'))    else:        print('Incorrect input ,please input again!!')

很简单的一个程序，感觉别人写的思路不错，很条理，学习一下。
总结知识点有两个
1：优雅的enumerate函数，返回一个生成器对象：（index,item）的元组
2：print(‘product list :’.center(50,’-‘)) 可以居中打印，真好玩，哈哈