Java Exercises: Convert a hexadecimal to a octal number

Java Basic: Exercise-30 with Solution

Write a Java program to convert a hexadecimal to a octal number.

Hexadecimal number: This is a positional numeral system with a radix, or base, of 16. Hexadecimal uses sixteen distinct symbols, most often the symbols 0-9 to represent values zero to nine, and A, B, C, D, E, F (or alternatively a, b, c, d, e, f) to represent values ten to fifteen.

Octal number: The octal numeral system is the base-8 number system, and uses the digits 0 to 7.

Test Data:
Input any hexadecimal number: 40

Pictorial Presentation: Hexadecimal to Octal number

Sample Solution:

Java Code:

import java.util.Scanner;

public class Exercise30 {
 public static int hex_to_decimal(String s)
    {
             String digits = "0123456789ABCDEF";
             s = s.toUpperCase();
             int val = 0;
             for (int i = 0; i < s.length(); i++)
             {
                 char c = s.charAt(i);
                 int d = digits.indexOf(c);
                 val = 16*val + d;
             }
             return val;
    }
    public static void main(String args[])
    {
        String hexdec_num;
        int dec_num, i=1, j;
        int octal_num[] = new int[100];
        Scanner in = new Scanner(System.in);
		
        System.out.print("Input a hexadecimal number: ");
        hexdec_num = in.nextLine();
        
        // Convert hexadecimal to decimal
        
        dec_num = hex_to_decimal(hexdec_num);
        
        //Convert decimal to octal
        
        while(dec_num != 0)
        {
            octal_num[i++] = dec_num%8;
            dec_num = dec_num/8;
        }
		
        System.out.print("Equivalent of octal number is: ");
        for(j=i-1; j>0; j--)
        {
            System.out.print(octal_num[j]);
        }
		System.out.print("\n");
    }
}

Sample Output:

Input a hexadecimal number: 40                                                                                
Equivalent of octal number is: 100

Flowchart:

Java Code Editor:

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