How do I fix my if statement?

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Hi there I'm having some problems with a project for school. I have to use the lung algorithm to create a program to validate a credit card. The if statement at the bottom will not run and print the message at the end. Any help would be greatly appreciated.

C#

Card_Number = int ( input ( "Please enter your 16 digit credit card number:" ) )  
Total = 0
Card_Number_String = str ( Card_Number )
a = int ( Card_Number_String [ 0 ] )
b = int ( Card_Number_String [ 1 ] )
c = int ( Card_Number_String [ 2 ] )
d = int ( Card_Number_String [ 3 ] )
e = int ( Card_Number_String [ 4 ] )
d = int ( Card_Number_String [ 5 ] )
f = int ( Card_Number_String [ 6 ] )
g = int ( Card_Number_String [ 7 ] )
h = int ( Card_Number_String [ 8 ] )
i = int ( Card_Number_String [ 9 ] )
j = int ( Card_Number_String [ 10 ] )
k = int ( Card_Number_String [ 11 ] )
l = int ( Card_Number_String [ 12 ] )
m = int ( Card_Number_String [ 13 ] )
n = int ( Card_Number_String [ 14 ] )
o = int ( Card_Number_String [ 15 ] )

if ( a ) % 2 == 0:
    a_Doubled = ( a ) * 2
    if ( a ) > 10:
        Two_Digit_Number_One = ( a ) * 2 
        OneDigit1 = str ( Two_Digit_Number [ 0 ] )
        OneDigit2 = str ( Two_Digit_Number [ 1 ] )
        Two_Digit_Number_One_Sum = str ( ( One_Digit1 ) + ( One_Digit2 ) )
        print ( Two_Digit_Number_One_Sum )

What I have tried:

I've tried editing the if statement anyway I can think of.

Posted 16-Oct-16 17:10pm

Member 12796896

Updated 16-Oct-16 17:42pm

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PIEBALDconsult 17-Oct-16 0:58am

Not Lung; Luhn!
https://en.wikipedia.org/wiki/Luhn_algorithm
You're trying too hard. It's really very simple. And you should be able to do it without any ifs.

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Member 1091218 · Answer 1 · 2016-10-16T17:40:00

Solution 1

The if will work if the 16 digit number starts with an even number
eg:4234567891111110

Posted 16-Oct-16 17:40pm

Member 1091218

Patrice T · Answer 2 · 2016-10-16T17:42:00

This test :

Python

if ( a ) > 10:

will never do because a is a single digit.
Did you intend to use a_Doubled instead ?

You should learn to use the debugger as soon as possible. Rather than guessing what your code is doing, It is time to see your code executing and ensuring that it does what you expect.

The debugger allow you to follow the execution line by line, inspect variables and you will see that there is a point where it stop doing what you expect.
Debugger - Wikipedia, the free encyclopedia[^]
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]

The debugger is here to show you what your code is doing and your task is to compare with what it should do.
When the code don't do what is expected, you are close to a bug.

Advice: take a sheet of paper and try to do it by hand, your program should use the same procedure.