Question

(Base13 to decimal) Hitchhiker’s Guide to the Galaxy proposed that the answer to the ultimate question
was 42. It turned out that the corresponding question was ‘what is 9 times 6’. Some of you with a
modicum of Math skills might argue that is not right, but it is right if we are working with a base 13
system. This question requires you to input a 3-digit Base 13 number and convert it to its equivalent
decimal representation (note in Base 13 A is decimal 10, B is decimal 11, and C is decimal 12). Here are
some sample runs that your java program might produce:
<Output>
Enter a three-digit Base 13 string: 042
The decimal number for 042 is 54

i can not use array.

Answer 1

import java.util.Scanner;

public class Base13Conversion {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a three-digit Base 13 string: ");
        String s = in.next();
        int d = 0;
        char ch;
        for (int i = 0; i < s.length(); i++) {
            d *= 13;
            ch = s.charAt(i);
            if (ch >= '0' && ch <= '9')
                d += ch - '0';
            else if (ch == 'a' || ch == 'A')
                d += 10;
            else if (ch == 'b' || ch == 'B')
                d += 11;
            else if (ch == 'c' || ch == 'C')
                d += 12;
        }
        System.out.println("The decimal number for " + s + " is " + d);
    }
}