Write a Java Program to Convert Octal Number to Decimal and vice-versa

Converting between octal and decimal numbers is a fundamental skill in computer programming.

In this tutorial, we’ll show you how to write a Java program to convert octal numbers to decimal and vice-versa.

Octal Number to Decimal Conversion

An octal number is a base-8 number system that uses eight digits, namely 0, 1, 2, 3, 4, 5, 6, and 7.

To convert an octal number to a decimal number, you can use the following formula:

decimal = sum(oi * 8i), i=0 to n-1

where oi is the ith digit of the octal number, n is the number of digits in the octal number, and the exponent i increases from 0 to n-1.

Here’s a Java program that converts an octal number to a decimal number:

import java.util.Scanner;

public class OctalToDecimal {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter an octal number: ");
        String octal = input.nextLine();
        int decimal = 0;
        for (int i = 0; i < octal.length(); i++) {
            int digit = octal.charAt(i) - '0';
            decimal += digit * Math.pow(8, octal.length() - i - 1);
        }
        System.out.println("Decimal equivalent: " + decimal);
    }
}

This program prompts the user to enter an octal number and uses a loop to calculate its decimal equivalent using the formula mentioned above.

Finally, it prints the decimal equivalent to the console.

Decimal to Octal Conversion

A decimal number is a base-10 number system that uses ten digits, namely 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.

To convert a decimal number to an octal number, you can use the following algorithm:

Divide the decimal number by 8
Record the remainder
Divide the quotient by 8
Record the remainder
Repeat steps 3 and 4 until the quotient becomes 0
The octal number is the sequence of remainders in reverse order

Here’s a Java program that converts a decimal number to an octal number:

import java.util.Scanner;

public class DecimalToOctal {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter a decimal number: ");
        int decimal = input.nextInt();
        String octal = "";
        while (decimal != 0) {
            int remainder = decimal % 8;
            octal = remainder + octal;
            decimal /= 8;
        }
        System.out.println("Octal equivalent: " + octal);
    }
}

This program prompts the user to enter a decimal number and uses a loop to calculate its octal equivalent using the algorithm mentioned above.

Finally, it prints the octal equivalent to the console.