<分区>
我正在尝试在循环中创建异常处理。
我已经创建了以下代码，我想在 userId1 和 userid2 中放置一个异常(exception)。
例如，用户总数是943，那么当用户输入一个大于943的userId时，抛出一个异常消息'Sorry, this userId does not exist'并重新开始循环.
我试着用 try: 和 except KeyError: 但没有正确播放，或者我没有按正确的顺序书写。
怎么写呢？
exit=False
while exit is False:
print("Hello Lady or Gentleman, this is a very primitive movie recommnedation system, please follow the instructions below : ")
print("---------------------------------------------------------------------------")
print("1) If you would like to find the difference 1 please press 1")
print("2) If you would like to find the difference 2 please press 2")
print("3) If you would like to exit, then press 0")
option=False
while option is False:
print("Εnter what would you like to find please :",end=" ")
option=input();
if option =='1':
print("The total number of users is 943, so you should enter 2 user_ids lower than 944")
print('---------------------')
print("Enter the first userId please :",end=" ")
user1 = input();
print("Enter the second userId please :",end=" ")
user2 = input();
elif option == '2':
print("The total number of movies is 1682, so you should enter 2 movie_ids lower than 1683")
print('-------------------')
print("Enter the first bookId please :",end=" ")
bookId1 = input();
print("Enter the second bookId1 please :",end=" ")
bookId2= input();
elif option == '0':
exit = True
print("Thank you very much")
break
else:
option = False
print("This option is not valid, Please try again!")