1 while True: 2 salary = input("please input your salary:") 3 if salary.isdigit(): 4 salary=int (salary) 5 break 6 else: 7 print("Invalid input! please input a number:") 8  9 product_cart = [[‘iphone6s‘,5800], #定义商品列表10 [‘macbook‘,9000],11 [‘coffee‘,30],12 [‘python book‘,80],13 [‘bicycle‘,1500]14  ]15 shopping_cart = [] #定义购物车16 balance=salary17 18 while True:19 for i,v in enumerate(product_cart,1): #enumerate参数将商品列表循环打印，并且第一行从1开始 加上序号20 print(i,v)21 22 choise = input("please input your selection[typing ‘q‘ to quit]:")23 if choise.isdigit(): #判断是否是数字24 choise=int(choise)25 if choise >=1 and choise<=len(product_cart): #判断输入的字符是否符合商品列表所在的范围26 sales =product_cart[choise-1] #将用户选择的商品赋值给sales27 if balance >=sales[1]: #判断余额是否足够购买该商品28 balance -=sales[1] #购买完后将余额减去商品价格29 shopping_cart.append(sales) #将商品加入购物车30 print("your balance is %s :"%balance)31 print()32 else:33 print("your balance is %s,not enough to buy this one，please try another products!"%balance,)34 print()35 36 37 else:38 print("no such a selection")39 elif choise == ‘q‘: #判断是否是q选择退出40 print("your shopping cart is:")41 for i, v in enumerate(shopping_cart, 1): 42 print(i, v)43 break44 else:45 print("Invalid typing.please typing a number!") #非数字执行的操作