Python 多条件输入验证：语法正确？

Question

I've created a simple program where the user is prompted to guess a number between 1 and 20. Originally my program just prompted the user if their input was too high or low. Later on I added a function that prompted the user when their input is out of range (below 1 or above 20). The program works fine, however I was wondering if my format and syntax are "correct" or "proper".

magic_number = 12

# get input from user 
user_number = int(input('What is the magic number between 1 and 20 ? '))

# attempting to create an efficient while loop
while True:
    if user_number < 12 and user_number >= 1:
        # error message 
        print('Your number is too low. Please try again.')
        # ask for input again
        user_number = int(input('What is the magic number between 1 and 20 ? '))
    elif user_number > 12 and user_number <= 20:
        # error message
        print('Your number is too high. Please try again.')
        # ask for input again
        user_number = int(input('What is the magic number between 1 and 20? '))
    elif user_number < 1 or user_number > 20:
        # error message
        print('Your number is out of range. Please try again.')
        # ask for input again
        user_number = int(input('What is the magic number between 1 and 20? '))
    elif user_number == magic_number:
        print('Congratulations! You have guessed the magic number.')
        break

Answer 1

If you're interested in the official "Pythonic" way to format your code, that's what the PEP8 specification is all about: https://www.python.org/dev/peps/pep-0008/ .

Looking at your code, I have a couple of suggestions to possibly make things a little cleaner and easier to maintain:

1. Try to avoid hard-coding the same constant value (eg 1, 20, 12) in multiple places. That way if you want to change them later, you only have to change it in one place.
2. Try to avoid repeat logic in multiple places if you can help it (or move it into a function) for the same reason as #1. If you have a bug you only have to fix it in one spot.

There's a lot of things you could do, but here's an example of what it might look like just following those two comments:

magic_number = 12

min_number = 1
max_number = 20

# attempting to create an efficient while loop
while True:
    # get input from user
    user_number = int(input('What is the magic number between {} and {} ? '.format(min_number, max_number)))

    if user_number < magic_number and user_number >= min_number:
        print('Your number is too low. Please try again.')
    elif user_number > magic_number and user_number <= max_number:
        print('Your number is too high. Please try again.')
    elif user_number < min_number or user_number > max_number:
        print('Your number is out of range. Please try again.')
    elif user_number == magic_number:
        print('Congratulations! You have guessed the magic number.')
        break

Maybe some future things to try out might be figuring out how to handle if the user doesn't enter a number or using the random module to generate a different magic number each time instead of hard-coding it to 12.

Good luck and hope that helps.