Hans Luhn Algorithm Algorithm Description: Credit card numbers follow certain pa
ID: 3775428 • Letter: H
Question
Hans Luhn Algorithm Algorithm Description: Credit card numbers follow certain patterns. A credit card number must have between 13 and 16 digits. It must start with: 4 for Visa cards 5 for Master cards 36 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 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 MIS 2845 – Section 001 Group Project Spring 2016 2
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. 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 MIS 2845 – Section 001 Group Project Spring 2016 3
Project Part II
(The Account class) Design a class named Account that contains: • A long integer data field named accoutNumber for the account (default 0). • A no-arg constructor that creates a default account. • A constructor that creates an account with the specified accoutNumber. • A method named accountType(Long number) that returns a boolean. The method determines if the account type is a credit card. The method will use the CardValidation class to check if the account number passed in the method is a valid credit card number. If it is not then the method returns True.
(The CardValidation class) Design a class named CardValidation that contains: • A long integer data field named cardNumber for the account (default 0). • A no-arg constructor that creates a default CardValidation. • A constructor that creates an account with the specified cardNumber. • A static method named isValid(long cardNumber) that returns a Boolean.(True or False) The method determines if the card number is a valid credit card number. The method will return true if the card number is valid. The method will use the Hans Luhn logarithm. Almost all credit card numbers are generated following this validity check, commonly known as the Luhn check or the Mod 10 check. The logarithm is explained above in Part
Write a class validaccount that will read a file (accounts.txt) the file contains last names and and account numbers as listed:
Jones 369218658389641
Smith 6011781008881301
Wayne 5551066751345482
Wines 4809134775860430
Biggie 9925689541232325
Luke 7586425896325410
Brandy 4388576018410707
Ryan 2458912425860439
Explanation / Answer
Credit card numbers follow certain patterns. A credit card must have between 13 and 16 digits. It must start with:
• 4 for Visa cards
• 5 for Master cards
• 37 for American Express 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 know as the Luhn check or the Modulus 10 check, which can be described as follows. For illustration, consider the card number 4388576018402625.
1. Double every second digit from right to left. If doubling of a digit results in a 2-digit number, add up the two digits to get a single-digit number.
2 x 2 = 4
2 x 2 = 4
4 x 2 = 8
1 x 2 = 2
6 x 2 = 12 (1+2= 3)
5 x 2 = 10 (1+0= 1)
8 x 2 = 16 (1+6= 7)
4 x 2 = 8
1. Add all the single digit numbers from step 1 4 + 4 +8 + 2 +3 + 1 + 7 + 8 = 37
2. Add all digits in the odd places from right to left in the card number
5 + 6 + 0 + 8 + 0 + 7 + 8 + 3 = 37
1. Sum the results from step 2 and step 3 37 + 37 = 74
2. If the result from step is divisible by 10, the card number is valid; otherwise, it’s invalid. For example, the number 4388576018402625 is invalid, but the number 4388576018410707 is a valid Visa card; the number 6011000593748745 is invalid, but the number 6011000593748746 is a valid Discover card.
The follwing code:
import java.util.Scanner;
public class CreditCardValidation {
public static boolean isValid(long number) {
int total = sumOfDoubleEvenPlace(number) + sumOfOddPlace(number);
if ((total % 10 == 0) && (prefixMatched(number, 1) == true) && (getSize(number)>=13 ) && (getSize(number)<=16 )) {
return true;
} else {
return false;
}
}
public static int getDigit(int number) {
if (number <= 9) {
return number;
} else {
int firstDigit = number % 10;
int secondDigit = (int) (number / 10);
return firstDigit + secondDigit;
}
}
public static int sumOfOddPlace(long number) {
int result = 0;
while (number > 0) {
result += (int) (number % 10);
number = number / 100;
}
return result;
}
public static int sumOfDoubleEvenPlace(long number) {
int result = 0;
long temp = 0;
while (number > 0) {
temp = number % 100;
result += getDigit((int) (temp / 10) * 2);
number = number / 100;
}
return result;
}
public static boolean prefixMatched(long number, int d) {
if ((getPrefix(number, d) == 4)
|| (getPrefix(number, d) == 5)
|| (getPrefix(number, d) == 3)) {
if (getPrefix(number, d) == 3) {
System.out.println(" Visa Card ");
} else if (getPrefix(number, d) == 5) {
System.out.println(" Master Card ");
} else if (getPrefix(number, d) == 3) {
System.out.println(" American Express Card ");
}
return true;
} else {
return false;
}
}
public static int getSize(long d) {
int count = 0;
while (d > 0) {
d = d / 10;
count++;
}
return count;
}
public static long getPrefix(long number, int k) {
if (getSize(number) < k) {
return number;
} else {
int size = (int) getSize(number);
for (int i = 0; i < (size - k); i++) {
number = number / 10;
}
return number;
}
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.print("Enter a credit card number as a long integer: ");
long input = sc.nextLong();
if (isValid(input) == true) {
System.out.println(" " + input + " is Valid. ");
} else {
System.out.println(" " + input + " is Invalid. ");
}
}
}
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