Question

ISBN-13 is a new standard for identifying books. It uses 13 digits d1d2d3d4d5d6d7d8d9d10d11d12d13. The last digit d13 is a checksum, which is calculated from the other digits using the following formula: 10 - (d1 3d2 d3 3d4 d5 3d6 d7 3d8 d9 3d10 d11 3d12) % 10 If the checksum is 10, replace it with 0. Your program should read the input as a string.

Answer 1

Answer:

// Scanner class is imported to allow program

// read input from user

import java.util.Scanner;

// Solution class is created

public class Solution {

// main method that begin program execution

public static void main(String[] strings) {

// Scanner object scan is created

// it receive input via the keyboard

Scanner scan = new Scanner(System.in);

// a prompt is displayed for user to enter 12 digits of ISBN

System.out.print("Enter the first 12 digits of an ISBN as string: ");

// user input is assigned to input

String input = scan.next();

//if length of input is not 12, program display error message and quit

if (input.length() != 12) {

System.out.println(input + " is Invalid input");

System.exit(0);

}

// 0 is assigned to checkSum

int checkSum = 0;

// for loop that goes through the string and does the computation

for (int i = 0; i < input.length(); i++) {

// if the index is even

if ((i + 1) % 2 == 0) {

checkSum += (input.charAt(i) - '0') * 3;

}

// if the index is odd

else

{

checkSum += input.charAt(i) - '0';

}

}

// modulo 10 of checkSum is assigned to checkSum

checkSum %= 10;

// checkSum is substracted from 10

checkSum = 10 - checkSum;

// if checkSum equals 10, 0 is concatenated with input

// else input is concatenated with checkSum

if (checkSum == 10) input += "0";

else input += checkSum;

// the new value of the isbn-13 is displayed

System.out.println("The ISBN-13 number is " + input);

}

}

Explanation:

The program is written in Java and well commented.

A sample of program output during execution is also attached.