Question

Write a Java program to convert octal (integer) numbers into their decimal number equivalents (exactly the opposite of what you have done in Assignment 4). Make sure that you create a new Project and Java class file for this assignment. Your file should be named “Main.java”. You can read about octal-to-decimal number conversions on wikepedia

Assignment 4 is at the bottom

Objective

Your program should prompt the user to enter a number of no greater than 8 digits. If the user enters a number greater than 8 digits or a value less than 0, it should re-prompt the user to enter a number again*. You do not need to check if the digits are valid octal numbers (0-7), as this is guaranteed.

Instructions

• Note that the conversion logic should be in a separate method (not the main() method).
• main() method will take the input from the user and pass it to the conversion() method.
• The conversion() method will convert the input octal to decimal and print the output.
  • No return value is required.
  • a sample structure is shown below.

• Use a sentinel while loop to solve the problem.
• Ideally, you should copy your assignment 4 code here and modify it to serve the new purpose. This will save you time.

• USE ONLY INTEGER VARIABLES FOR INPUTS AND OUTPUTS.
• USE ONLY THE TECHNIQUES TAUGHT IN CLASS

main(){

int oct = user input;

conversion(oct);

}

void conversion(int o){

// logic goes here.

print(decimal);

}

Goals

• more experience in WHILE loop.
• experience in Java Methods
• logical thinking

Sample Runs

Sample Program Run (user input is underlined)

Enter up to an 8-digit octal number and I will convert it for you: 77777777

16777215

Sample Program Run (user input is underlined)

Enter up to an 8-digit octal number and I will convert it for you: 775002

260610

Sample Program Run (user input is underlined)

Enter up to an 8-digit octal number and I will convert it for you: 0

0

Sample Program Run (user input is underlined)

Enter up to an 8-digit octal number and I will convert it for you: 55

45

Sample Program Run (user input is underlined)

Enter up to an 8-digit octal number and I will convert it for you: 777777777

Enter up to an 8-digit octal number and I will convert it for you: 777777777

Enter up to an 8-digit octal number and I will convert it for you: 700000000

Enter up to an 8-digit octal number and I will convert it for you: 77

63

Assignment 4:

// Main.java : Java program to convert decimal number to octal

import java.util.Scanner;

public class Main {

public static void main(String[] args) {

int inputNum, convertedNum;

Scanner scan = new Scanner(System.in);

// Input of integer number in decimal

System.out.print("Please enter a number between 0 and 2097151 to convert: ");

inputNum = scan.nextInt();

// validate the number

if(inputNum < 0 || inputNum > 2097151)

System.out.println("UNABLE TO CONVERT");

else

{

int weight=0; // weight of the digit, used for converting to octal

convertedNum = 0; // variable to store the number in octal

int temp = inputNum;

int digit;

// loop that continues till we convert the entire number to octal

while(temp > 0)

{

digit = (temp%8); // get the remainder when the number is divided by 8

// multiply the digit with its weight and add it to convertedNum

convertedNum += digit*Math.pow(10, weight);

temp = temp/8; // remove the last digit from the number

weight++; // increment the weight

}

// display the integer in octal

System.out.printf("Your integer number " + inputNum + " is %07d in octal",convertedNum);

}

scan.close();

}

}

Answer 1

import java.util.Scanner;

public class OctalToDecimal {
   public static void main(String[] args) {
       Scanner sc = new Scanner(System.in);
       System.out.println("Enter up to an 8-digit octal number and I will convert it for you: ");
       int num = sc.nextInt();
       conversion(num);
   }

   private static void conversion(int n) {
       int num = n;
       int dec_value = 0;

       // starting from 1 as 8^0 is 1
       int base = 1;
       int temp = num;
       while (temp > 0) {
           // fetching last digit using %
           int last_digit = temp % 10;
           // removing last digit
           temp = temp / 10;

           dec_value += last_digit * base;
           // increseing base to next like 8^1,8^2..
           base = base * 8;
       }
       System.out.println(dec_value);
   }
}

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<terminated> Octal ToDecimal [Java Application] C:\Soft\PegaEclipse-win64-4.5.2.2\PegaEclipse-win64-4.5 Enter up to an 8-digit octal number and I will convert it for you: 775002 260610