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,'-'))product_list = [  ('Iphone',5888),  ('Mac Air',8000),  ('XiaoMi',19.9),  ('coffee',30),  ('Tesla',820000),  ('Bike',700),  ('Cloth',200)]shop_car = []#推出標志位exit_flag = 0while exit_flag is not True:  print('product list :'.center(50,'-'))  for item in enumerate(product_list):    index = item[0]   #獲得商品序號    p_name = item[1][0]  #獲得商品名稱    p_price= item[1][1]  #獲得商品價格    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): #輸入的商品序號要在范圍之內(nèi)      p_item = product_list[user_choice] #選擇的商品      if p_item[1] <= salary: #買得起        shop_car.append(p_item) #放入購物車        salary -= p_item[1] #減錢        print('purchased products are:'.center(40, '-'))        for item in shop_car:          print(item)        print('Your balance is [%s]' % salary)      else:          #買不起        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!!')

input your salary:10000-----------welcome to our shoping mall------------------------------product list :------------------0 Iphone 58881 Mac Air 80002 XiaoMi 19.93 coffee 304 Tesla 8200005 Bike 7006 Cloth 200[q=quit,c=check] what do you want to buy?:0added [[('Iphone', 5888)]] into shop car ,yourcurrent balence is 4112------------------product list :------------------0 Iphone 58881 Mac Air 80002 XiaoMi 19.93 coffee 304 Tesla 8200005 Bike 7006 Cloth 200[q=quit,c=check] what do you want to buy?:1Your balance is [4112],cannot buy the product!------------------product list :------------------0 Iphone 58881 Mac Air 80002 XiaoMi 19.93 coffee 304 Tesla 8200005 Bike 7006 Cloth 200[q=quit,c=check] what do you want to buy?:cshop car list are [[('Iphone', 5888)]],your balance is 4112------------------product list :------------------0 Iphone 58881 Mac Air 80002 XiaoMi 19.93 coffee 304 Tesla 8200005 Bike 7006 Cloth 200[q=quit,c=check] what do you want to buy?:4Your balance is [4112],cannot buy the product!------------------product list :------------------0 Iphone 58881 Mac Air 80002 XiaoMi 19.93 coffee 304 Tesla 8200005 Bike 7006 Cloth 200[q=quit,c=check] what do you want to buy?:q--------purchased products are:---------('Iphone', 5888)------------------END ------------------Your balance is [4112]Process finished with exit code 0

>>> print('product list :'.center(50,'-'))------------------product list :------------------

>>> for item in enumerate(product_list):print(item)(0, ('Iphone', 5888))(1, ('Mac Air', 8000))(2, ('XiaoMi', 19.9))(3, ('coffee', 30))(4, ('Tesla', 820000))(5, ('Bike', 700))(6, ('Cloth', 200))