How to fix the error message?

Question

This is the first time im writing a program with python and im trying to only allow the user to input 8 digits. I managed to do this and every time i enter more or less than 8 it gives the error message which is good but after that if i enter 8 digits it still gives the error message

    value3 = input("please enter your card number: ")
while not value3.isdigit():
    value3= input("please enter your card NUMBER: ")
if len(value3) > 8:
    while True:
        value3 = input("Error! Only 8 characters allowed!: ")
if len(value3) < 8:
    while True:
        value3 = input("Error! Only 8 characters allowed!: ")

i did that but now once I enter more or less digits the error message appears (which is good) but then if i enter the wrong amount again it just lets me through and doesn't show the error again — darius DEAnzo, Nov 09 '17 at 15:19
I think you'll find this page helpful: https://stackoverflow.com/questions/23294658/asking-the-user-for-input-until-they-give-a-valid-response — PM 2Ring, Nov 09 '17 at 15:20
I looked at it but it also uses while loops. Also its about the age as in 12<18 but i need it to be the amount of characters — darius DEAnzo, Nov 09 '17 at 15:26

score 2 · Answer 1 · answered Nov 09 '17 at 15:21

You should not use While True: in your if statements.

You can do something like this:

value3 = input("please enter your card number: ")

while True:
    if not value3.isdigit():
        value3= input("please enter your card NUMBER, Only digits are allowed: ")
        continue
    elif len(value3) != 8:
        value3 = input("Error! Only 8 digits allowed!: ")
    else:
        print("Valid card number")
        break

score 1 · Answer 2 · answered Nov 09 '17 at 15:15

1

Well it appears that you have the "error messages" in while loops with the condition always set to true. So no matter what you enter, your program is still stuck in that while loop. A better approach might be to define an "error function" that gets called when the input is more/less than 8.

answered Nov 09 '17 at 15:15

SuperStew

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how would I be able to do that? – darius DEAnzo Nov 09 '17 at 15:21

How to fix the error message?

2 Answers2