MUST IMPLEMENT at least 4 of the 7 METHODS LISTED IN THE BOOK!!!! Credit card nu

Question

MUST IMPLEMENT at least 4 of the 7 METHODS LISTED IN THE BOOK!!!!

Credit card numbers follow certain patterns. A credit card number must have 16 digits. It must start with:

4 for Visa cards

5 for Master 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 if a card number is entered correctly or if a credit card is scanned correctly by a scanner. Almost all 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 * 2 = 4

2 * 2 = 4

4 * 2 = 8

1 * 2 = 2

6 * 2 = 12 (1 + 2 = 3)

5 * 2 = 10 (1 + 0 = 1)

8 * 2 = 16 (1 + 6 = 7)

4 * 2 = 8

2. Now add all single-digit numbers from Step 1.

4 + 4 + 8 + 2 + 3 + 1 + 7 + 8 = 37

3. Add all digits in the odd places from right to left in the card number.

   6 + 6 + 0 + 8 + 0 + 7 + 8 + 3 = 38

4. Sum the results from Step 2 and Step 3.

37 + 38 = 75

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 a long integer. Display whether the number is valid or invalid.

Here are sample runs of the program:

Sample 1:

Enter a credit card number as a long integer: 4246345689049834

4246345689049834 is invalid

Sample 2:

Enter a credit card number as a long integer: 4388576018410707

4388576018410707 is valid

Analysis: TAKE AS MUCH SPACE AS NEEDED FOR THESE EXPLANATIONS.

(Describe the problem including input and output in your own words. If a class structure is used turn in the UML design)

Design:

(Describe the major steps for solving the problem using the diagram like the one in the book Figure 6.11, page 228)

Testing: (Describe how you test this program). Attach printed outputs of at least 5 different test runs (must contain test cases for Visa, Master, Discover cards, valid or invalid).

Coding: Attach a printed copy of your program WITH OUTPUT as last pages of this document.

Explanation / Answer

The question does not specify the programming language. So I assumed it to be Java , since it mentions the word "implement method". Also the 7 methods listed in the book are not specified. So implemented the program to validate the card number.

Hope it helps.

import java.util.Scanner;

public class ValidateCard {

//will return the sum of all digits in n
private static int sumDigits(int n)
{
int sum = 0;
  
while (n != 0)
{
//get the last digit by getting remainder of division by 10
int digit = n % 10;
sum += digit;
n /= 10; //for next iteration drop off the last digit, by dividing by 10
}
  
return sum;
}


private static boolean isValid(long cardnum)
{
long n = cardnum;
boolean odd = true; //boolean to indicate whether we are fetching the odd or even positioned digit
int oddSum = 0;
int evenSum = 0;
  
//extract digits from right to left using remainders from division by 10
while(n != 0)
{
int digit =(int) (n % 10);
if(odd) //are we handling a digit in odd position from right to left
{
oddSum += digit; //add the odd digit to oddSum
}
else //even position from right to left
{
evenSum += sumDigits( 2 * digit); //add the result of summing the digits after doubling the digit
}

odd = !odd; //for next iteration toggle
n /= 10; //drop off the last digit
}

int total = oddSum + evenSum; //add up the sums of odd possition and even positions
  

if(total % 10 == 0) //if the total is divisble by 10, then its valid
return true;
else
return false;

}

public static void main(String[] args) {
Scanner keybd = new Scanner(System.in);
long cardnum = 1;
  
System.out.print("Enter a credit card number as long integer: ");
cardnum = keybd.nextLong();
  
if(isValid(cardnum))
System.out.println(cardnum + " is valid");
else
System.out.println(cardnum + " is invalid");

}

}

output

Enter a credit card number as long integer: 4388576018402626
4388576018402626 is invalid

Enter a credit card number as long integer: 4388576018410707
4388576018410707 is valid

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