Python credit card validation
(Financial: credit card number validation) Credit card numbers follow certain patterns: It must have between 13 and 16 digits, and the number must start with:
■ 4 for Visa cards
■ 5 for MasterCard credit cards
■ 37 for American Express cards
■ 6 for Discover cards
In 1954, Hans Luhn of IBM proposed an algorithm for validating credit card numbers. The algorithm is useful to determine whether a card number is entered correctly or whether a credit card is scanned correctly by a scanner. Credit card numbers are generated following this validity check, commonly known as the Luhn check or the Mod 10 check, which can be described as follows (for illustration,
consider the card number 4388576018402626):
1. Double every second digit from right to left. If doubling of a digit results in a
two-digit number, add up the two digits to get a single-digit number.
2. Now add all single-digit numbers from Step 1.
3. Add all digits in the odd places from right to left in the card number.
4. Sum the results from Steps 2 and 3.
5. If the result from Step 4 is divisible by 10, the card number is valid; otherwise, it is invalid. For example, the number 4388576018402626 is invalid, but the number 4388576018410707 is valid.
Write a program that prompts the user to enter a credit card number as an integer. Display whether the number is valid or invalid.
newNumberList = []
number = eval(input('Enter credit card number: '))
k = ''
def getPrefix(number, k):
numStraing = str(number)
numStraing = numStraing[:2]
k = numStraing
if k[0] == '4' or k[0] == '5' or k[0] == '6' or k == '37':
pass
else:
return False
def numberSize(number):
getPrefix(number, k)
if 13 <= len(str(number)) <= 16:
pass
else:
return False
def getDigit(number):
strNumber = str(number)
numberList = list(strNumber)
for i in numberList:
count = 0
num = int(i) * 2
if len(str(num)) == 1:
newNumberList.append(str(num))
elif len(str(num)) == 2:
for j in str(num):
count += int(j)
newNumberList.append(str(count))
return newNumberList
def sumOfDoubleEvenPlace(number):
getDigit(number)
sumEvenNumbers = 0
if len(str(number)) % 2 == 0:
for i in range(0, len(newNumberList), 2):
sumEvenNumbers += int(newNumberList[i])
else:
for i in range(1, len(newNumberList), 2):
sumEvenNumbers += int(newNumberList[i])
return sumEvenNumbers
def sumOfOddPlace(number):
strNumber = str(number)
numberList = list(strNumber)
sumOddNumbers = 0
if len(str(number)) % 2 != 0:
for i in range(0, len(numberList), 2):
sumOddNumbers += int(numberList[i])
else:
for i in range(1, len(numberList), 2):
sumOddNumbers += int(numberList[i])
return sumOddNumbers
def isValid(number):
numberSize(number)
sum = sumOfOddPlace(number) + sumOfDoubleEvenPlace(number)
print(sum)
if sum % 10 == 0:
return True
else:
return False
print(isValid(number))
SOLUTION:
Enter credit card number: 4388576018402626
75
False
Enter credit card number: 4388576018410707
70
True
■ 4 for Visa cards
■ 5 for MasterCard credit cards
■ 37 for American Express cards
■ 6 for Discover cards
In 1954, Hans Luhn of IBM proposed an algorithm for validating credit card numbers. The algorithm is useful to determine whether a card number is entered correctly or whether a credit card is scanned correctly by a scanner. Credit card numbers are generated following this validity check, commonly known as the Luhn check or the Mod 10 check, which can be described as follows (for illustration,
consider the card number 4388576018402626):
1. Double every second digit from right to left. If doubling of a digit results in a
two-digit number, add up the two digits to get a single-digit number.
2. Now add all single-digit numbers from Step 1.
3. Add all digits in the odd places from right to left in the card number.
4. Sum the results from Steps 2 and 3.
5. If the result from Step 4 is divisible by 10, the card number is valid; otherwise, it is invalid. For example, the number 4388576018402626 is invalid, but the number 4388576018410707 is valid.
Write a program that prompts the user to enter a credit card number as an integer. Display whether the number is valid or invalid.
newNumberList = []
number = eval(input('Enter credit card number: '))
k = ''
def getPrefix(number, k):
numStraing = str(number)
numStraing = numStraing[:2]
k = numStraing
if k[0] == '4' or k[0] == '5' or k[0] == '6' or k == '37':
pass
else:
return False
def numberSize(number):
getPrefix(number, k)
if 13 <= len(str(number)) <= 16:
pass
else:
return False
def getDigit(number):
strNumber = str(number)
numberList = list(strNumber)
for i in numberList:
count = 0
num = int(i) * 2
if len(str(num)) == 1:
newNumberList.append(str(num))
elif len(str(num)) == 2:
for j in str(num):
count += int(j)
newNumberList.append(str(count))
return newNumberList
def sumOfDoubleEvenPlace(number):
getDigit(number)
sumEvenNumbers = 0
if len(str(number)) % 2 == 0:
for i in range(0, len(newNumberList), 2):
sumEvenNumbers += int(newNumberList[i])
else:
for i in range(1, len(newNumberList), 2):
sumEvenNumbers += int(newNumberList[i])
return sumEvenNumbers
def sumOfOddPlace(number):
strNumber = str(number)
numberList = list(strNumber)
sumOddNumbers = 0
if len(str(number)) % 2 != 0:
for i in range(0, len(numberList), 2):
sumOddNumbers += int(numberList[i])
else:
for i in range(1, len(numberList), 2):
sumOddNumbers += int(numberList[i])
return sumOddNumbers
def isValid(number):
numberSize(number)
sum = sumOfOddPlace(number) + sumOfDoubleEvenPlace(number)
print(sum)
if sum % 10 == 0:
return True
else:
return False
print(isValid(number))
SOLUTION:
Enter credit card number: 4388576018402626
75
False
Enter credit card number: 4388576018410707
70
True
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