python购物车程序代码

''''' Created on 2017年9月4日  @author: len '''   product_list = [   ('Robot',200000),   ('MacPro',12000),   ('Iphone8',8888),   ('Hello World',1200),         ]  shopping_list = [] user_salary=input("请输入你的工资：") if user_salary.isdigit():   user_salary = int(user_salary)   while True:     print("商品如下：")     for index,item in enumerate(product_list):               print (index,item)     user_choice = input("请输入要购买的商品编号：")     if user_choice.isdigit():       user_choice = int(user_choice)       if user_choice  -1:         p_item = product_list[user_choice]         if user_salary>=p_item[1]:           shopping_list.append(p_item)           user_salary-=p_item[1]           print("购买商品",p_item,"成功您的余额为",user_salary,"元！" )         else:           print("您的余额为",user_salary,"余额不足以购买此商品，购买失败！")                      else:         print("并无此产品！")     elif user_choice == "q":       print("--------shopping list-------")       for i in shopping_list:         print(i)       exit()     else:       print("invalidate！！！")