The International Standard Book Number (ISBN) is a unique numeric book identifier which is printed on every book. The ISBN is based upon a 10-digit code.
The ISBN is legal if:
1 × digit1 + 2 × digit2 + 3 × digit3 + 4 × digit4 + 5 × digit5 + 6 × digit6 + 7 × digit7 + 8 × digit8 + 9 × digit9 + 10 × digit10 is divisible by 11.
Example:
For an ISBN 1401601499
Sum = 1 × 1 + 2 × 4 + 3 × 0 + 4 × 1 + 5 × 6 + 6 × 0 + 7 × 1 + 8 × 4 + 9 × 9 + 10 × 9 = 253 which is divisible by 11.
Write a program to:
- Input the ISBN code as a 10-digit integer.
- If the ISBN is not a 10-digit integer, output the message "Illegal ISBN" and terminate the program.
- If the number is divisible by 11, output the message "Legal ISBN". If the sum is not divisible by 11, output the message "Illegal ISBN".
import java.util.Scanner;
public class wemakejavaeasyISBNCheck
{
public static void main(String args[]) {
Scanner in = new Scanner(System.in);
System.out.print("Enter the ISBN: ");
long isbn = in.nextLong();
int sum = 0, count = 0, m = 10;
while (isbn != 0) {
int d = (int)(isbn % 10);
count++;
sum += d * m;
m--;
isbn /= 10;
}
if (count != 10) {
System.out.println("Illegal ISBN");
}
else if (sum % 11 == 0) {
System.out.println("Legal ISBN");
}
else {
System.out.println("Illegal ISBN");
}
}
}