字符串中的数字介于最大和最小之间

Question

So I am trying to get my string to be verified between 1000 to 9999 and when I try to run this, it comes back saying it is unverified. Curious on how to fix this problem so that it can actually read the 4 digits that a user input as a string. I have it as a string for a reason and it works fine for other parts of my code. it is just this one specifically is giving me a hard time.

def choiceTwo(digitCode):

    max = 9999
    min = 1000

    digitCode = [int(num) for num in digitCode]
    for x in digitCode:

        if x > max:
            return True

        if x < min:
            return False

def main():

    digitCode = str(input("Please enter a 4 digit code: "))

    if choiceTwo(digitCode) is True:
            print("Number is verified!")

    else:
            print("ERROR not a valid ")

Answer 1

It's probably easier to do this straight in your if statement:

if int(digitCode) < int(max) and int(digitCode) > int(min):
    print("Number is verified!")
else:
    print("ERROR not a valid ")

Edit: I made sure that both digitCode, max, and min were all integers since you mentioned that you used them as strings elsewhere in the code.

Edit 2: Also, double check your statements inside your function; what happens if x is in between max and min (currently it only returns True if x > max).

Answer 2

Your checking if each number in the 4 digit code is between those two values. But each number is in the range 0-9 hence this won't be true. Well, not between those two values persay your first if condition if x > max is simpy checking if the number is greater than 9999 and then returning True. You need to nest your conditions together by using and / or > operators to check for a number between this range.

You shouldn't name your two variables min and max as they are built into python and you're overriding functionality. You can also combine your condition. If you're not wanting your range of accepted values to be inclusive just take of the = in <= in the below condition to exclude 9999 and 1000

You can drop the extra is True in your original if condition since just doing if (expression) will evaluate it's truth value or "truthiness".

I added a while loop that will continuously prompt the user to input 4 digit codes until they are indeed of length four and valid digits to prevent errors in your other function and validate the input.

You actually don't even need the else: return False since returning nothing will return None and be evaluated as not being True in your if condition, but I left this to keep it close to the original. You could declare min and max to be global (or local in your main()) function, either one, and simply use if _min <= int(digitCode) <= _max if you wanted to be succinct.

def choiceTwo(digitCode):

    _max = 9999
    _min = 1000

    if _min <= digitCode <= _max:
        return True
    else:
        return False

def main():

    digitCode = input("Please enter a 4 digit code: ")
    while not (digitCode.isdigit() and len(digitCode) == 4):
        digitCode = input("Please enter a 4 digit code: ")

    if choiceTwo(int(digitCode)):
        print("Number is verified!")

    else:
        print("ERROR not a valid ")
main()