Credit card validator (need help)

Question

Why I don't make test 3,4 , where I wrong?
Почему не получается пройти тест 3, 4. Где ошибка?
card=list(input())
stand=["1","2","3","4","5","6","7","8","9","0"]
for y in card:
if y not in stand:
print("not valid")
break
elif y in stand:
rev_card=card[::-1]
x=0
sec_card=[]
big=[]
for i in rev_card:
c=i
x+=1
if x%2==1:
c2=int(c)
c2*=2
sec_card.append(c2)
for b in sec_card:
b2=int(b)
if b2>9:
b2-=9
big.append(b2)
all_sum=sum(big)
if all_sum%10==0 and len(big)==16:
print("valid")
break
else:
print("not valid")
break

Answer 1

Is that this code coach?
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.

Sample Input:
4091131560563988

Sample Output:
valid

Answer 2

I took the sample Input and put it into your code and received "not valid". I then went through and added print statements to see what the code does.

I think you have 2 indentation errors. Check the line sec_card.append(c2) and big.append(2).
I also changed the len(big) to len(card) but I don't think that affects the result other than I like to check the original input instead of whatever is left after all the work your code does.

Answer 3

Sorry, see if this helps.

https://code.sololearn.com/cKDs9Bm1Wise/?ref=app

Answer 4

I'm sorry, I don't understand that. The sample input prints valid, so it shouldn't be cutting any numbers.

Answer 5

Ausgrindtube, yes, this code

Answer 6

I don't understand last words about check...
About checking two line, I don't know, where I can move this line, do you have ideas? I try move this line to the left, no affects. Move to the right, error.

Answer 7

Sorry, you help, I see what all number of card multiply 2 🙏🙏🙏

Answer 8

Thanks for the attention, but don't help, if move two line to the right, cut number of card😢

Answer 9

If move line to the right, program take in list sec_card only number, which true of operator if.

Answer 10

https://code.sololearn.com/cZfXkFxsNVb7/?ref=app

Answer 11

Smith Welder Интересно, но ничего не понятно, я не сильна в таких лаконичных кодах🙀 Скопировала в окно проверки, чёт все равно не то😳

Answer 12

Smith Welder спасибо, я ступила и не так как надо скопировала. Всё правильно написано, просто я баран 😢

Answer 13

Что именно не понятно?

Answer 14

Честно, весь код, и что там обозначено, мой уровень очень низкий, такого уровня кодировки никогда не видела...

Answer 15

Что такое g?
u первоначальное значение цифр номера карты
x так понимаю это каждая цифра номера карты после вычислений

Answer 16

g это порядковый номер цифры числа. Функция enumerate() пронумировывает всю строку от нуля и до конца.
Используйте функцию print() , если что либо не понятно.
print(g)

Answer 17

Спасибо за исчерпывающий ответ😊🤝