Program to Convert Octal Number to Binary Number

Given an Octal number as input, the task is to convert that number to Binary number.

Examples:

Input : Octal = 345
Output : Binary = 11100101
Explanation : 
Equivalent binary value of 3: 011
Equivalent binary value of 4: 100
Equivalent binary value of 5: 101

Input : Octal = 120
Output : Binary = 1010000

Octal Number: An Octal number is a positional numeral system with a radix, or base, of 8 and uses eight distinct symbols.
Binary Number: A Binary number is a number expressed in the base-2 binary numeral system, which uses only two symbols: which are 0 (zero) and 1 (one).

To convert an Octal number to Binary, the binary equivalent of each digit of the octal number is evaluated and combined at the end to get the equivalent binary number.

Below is the implementation of the above approach: 

C++

// C++ program to convert
// Octal number to Binary

#include <iostream>
using namespace std;

// Function to convert an
// Octal to Binary Number
string OctToBin(string octnum)
{
    long int i = 0;

    string binary = "";

    while (octnum[i]) {
        switch (octnum[i]) {
        case '0':
            binary += "000";
            break;
        case '1':
            binary += "001";
            break;
        case '2':
            binary += "010";
            break;
        case '3':
            binary += "011";
            break;
        case '4':
            binary += "100";
            break;
        case '5':
            binary += "101";
            break;
        case '6':
            binary += "110";
            break;
        case '7':
            binary += "111";
            break;
        default:
            cout << "\nInvalid Octal Digit "
                 << octnum[i];
            break;
        }
        i++;
    }

    return binary;
}

// Driver code
int main()
{
    // Get the Hexadecimal number
    string octnum = "345";

    // Convert Octal to Binary
    cout << "Equivalent Binary Value = "
         << OctToBin(octnum);

    return 0;
}

Java

// Java program to convert
// Octal number to Binary
import java.util.*;
class Solution
{

// Function to convert an
// Octal to Binary Number
static String OctToBin(String octnum)
{
    long i = 0;

    String binary = "";

    while (i<octnum.length()) {

        char c=octnum.charAt((int)i);
        switch (c) {
        case '0':
            binary += "000";
            break;
        case '1':
            binary += "001";
            break;
        case '2':
            binary += "010";
            break;
        case '3':
            binary += "011";
            break;
        case '4':
            binary += "100";
            break;
        case '5':
            binary += "101";
            break;
        case '6':
            binary += "110";
            break;
        case '7':
            binary += "111";
            break;
        default:
            System.out.println( "\nInvalid Octal Digit "+ octnum.charAt((int)i));
            break;
        }
        i++;
    }

    return binary;
}

// Driver code
public static void main(String args[])
{
    // Get the Hexadecimal number
    String octnum = "345";

    // Convert Octal to Binary
    System.out.println( "Equivalent Binary Value = "+ OctToBin(octnum));

}

}
//contributed by Arnab Kundu

Python3

# Python3 program to convert
# Octal number to Binary

# defining a function that returns
# binary equivalent of the number
def OctToBin(octnum):

    binary = "" # initialising bin as String

    # While loop to extract each digit
    while octnum != 0:

        # extracting each digit
        d = int(octnum % 10)
        if d == 0:

            # concatenation of string using join function
            binary = "".join(["000", binary])
        elif d == 1:

            # concatenation of string using join function
            binary = "".join(["001", binary])
        elif d == 2:

            # concatenation of string using join function
            binary = "".join(["010", binary])
        elif d == 3:

            # concatenation of string using join function
            binary = "".join(["011", binary])
        elif d == 4:

            # concatenation of string using join function
            binary = "".join(["100", binary])
        elif d == 5:

            # concatenation of string using join function
            binary = "".join(["101", binary])
        elif d == 6:

            # concatenation of string using join function
            binary = "".join(["110",binary])
        elif d == 7:

            # concatenation of string using join function
            binary = "".join(["111", binary])
        else:

            # an option for invalid input
            binary = "Invalid Octal Digit"
            break

        # updating the oct for while loop
        octnum = int(octnum / 10)

    # returning the string binary that stores
    # binary equivalent of the number
    return binary

# Driver Code
octnum = 345

# value of function stored final_bin
final_bin = "" + OctToBin(octnum)

# result is printed
print("Equivalent Binary Value =", final_bin)

# This code is contributed by Animesh_Gupta

C#

// C# program to convert Octal number to Binary

class GFG
{

// Function to convert an
// Octal to Binary Number
static string OctToBin(string octnum)
{
    int i = 0;

    string binary = "";

    while (i < octnum.Length)
    {

        char c = octnum[i];
        switch (c)
        {
        case '0':
            binary += "000";
            break;
        case '1':
            binary += "001";
            break;
        case '2':
            binary += "010";
            break;
        case '3':
            binary += "011";
            break;
        case '4':
            binary += "100";
            break;
        case '5':
            binary += "101";
            break;
        case '6':
            binary += "110";
            break;
        case '7':
            binary += "111";
            break;
        default:
            System.Console.WriteLine( "\nInvalid Octal Digit "+
                                                    octnum[i]);
            break;
        }
        i++;
    }

    return binary;
}

// Driver code
static void Main()
{
    // Get the Hexadecimal number
    string octnum = "345";

    // Convert Octal to Binary
    System.Console.WriteLine("Equivalent Binary Value = " +
                                         OctToBin(octnum));
}
}

// This code is contributed by mits

PHP

<?php
// PHP program to convert
// Octal number to Binary

// Function to convert an
// Octal to Binary Number
function OctToBin($octnum)
{
    $i = 0;

    $binary = (string)"";

    while ($i != strlen($octnum))
    {
        switch ($octnum[$i])
        {
        case '0':
            $binary.= "000";
            break;
        case '1':
            $binary .= "001";
            break;
        case '2':
            $binary .= "010";
            break;
        case '3':
            $binary .= "011";
            break;
        case '4':
            $binary .= "100";
            break;
        case '5':
            $binary .= "101";
            break;
        case '6':
            $binary .= "110";
            break;
        case '7':
            $binary .= "111";
            break;
        default:
            echo("\nInvalid Octal Digit ".
                             $octnum[$i]);
            break;
        }
        $i++;
    }
    return $binary;
}

// Driver code

// Get the Hexadecimal number
$octnum = "345";

/// Convert Octal to Binary
echo("Equivalent Binary Value = " .
                OctToBin($octnum));

// This code is contributed
// by PrinciRaj1992

Javascript

<script>

// JavaScript program to convert
// Octal number to Binary

// Function to convert an
// Octal to Binary Number
function OctToBin(octnum)
{
    let i = 0;

    let binary = "";

    while (i<octnum.length) {

        let c=octnum[i];
        switch (c) {
        case '0':
            binary += "000";
            break;
        case '1':
            binary += "001";
            break;
        case '2':
            binary += "010";
            break;
        case '3':
            binary += "011";
            break;
        case '4':
            binary += "100";
            break;
        case '5':
            binary += "101";
            break;
        case '6':
            binary += "110";
            break;
        case '7':
            binary += "111";
            break;
        default:
            document.write( "<br>Invalid Octal Digit "+ octnum[i]);
            break;
        }
        i++;
    }

    return binary;
}

// Driver code
// Get the Hexadecimal number
let octnum = "345";

// Convert Octal to Binary
document.write( "Equivalent Binary Value = "+ OctToBin(octnum));

// This code is contributed by avanitrachhadiya2155

</script>

Output:

Equivalent Binary Value = 011100101

Time complexity: O(n) where n is no of digits in a given number.
Auxiliary space: O(n) it is using extra space for binary string.

define function to convert octal to binary in python:

Approach:

n this program, we define a function called octal_to_binary that takes an octal number as input and returns its binary equivalent.

The function works by first converting the octal number to decimal using the repeated division by 8 technique. Once we have the decimal equivalent, we can convert it to binary using the repeated division by 2 technique.

Finally, we call the octal_to_binary function with a sample octal number of 777, and then print the binary equivalent using an f-string.

C++

#include <iostream>
#include <cmath>
using namespace std;

int octal_to_binary(int octal) {
    // Converting Octal to Decimal
    int decimal = 0;
    int power = 0;
    while (octal != 0) {
        decimal += (octal % 10) * pow(8, power);
        octal /= 10;
        power++;
    }

    // Converting Decimal to Binary
    int binary = 0;
    int digit_place = 1;
    while (decimal != 0) {
        binary += (decimal % 2) * digit_place;
        decimal /= 2;
        digit_place *= 10;
    }

    return binary;
}

int main() {
    // Sample Input
    int octal_number = 777;

    // Octal to Binary Conversion
    int binary_number = octal_to_binary(octal_number);

    // Output
    cout << binary_number << endl;

    return 0;
}

Java

import java.util.Scanner;

public class Main {
    public static int octal_to_binary(int octal)
    {
        // Converting Octal to Decimal
        int decimal = 0;
        int power = 0;
        while (octal != 0) {
            decimal += (octal % 10) * Math.pow(8, power);
            octal /= 10;
            power++;
        }

        // Converting Decimal to Binary
        int binary = 0;
        int digit_place = 1;
        while (decimal != 0) {
            binary += (decimal % 2) * digit_place;
            decimal /= 2;
            digit_place *= 10;
        }

        return binary;
    }

    public static void main(String[] args)
    {
        // Sample Input
        int octal_number = 777;

        // Octal to Binary Conversion
        int binary_number = octal_to_binary(octal_number);

        // Output
        System.out.println(binary_number);
    }
}

Python3

# Octal to Binary Conversion Function
def octal_to_binary(octal):
    # Converting Octal to Decimal
    decimal = 0
    power = 0
    while octal != 0:
        decimal += (octal % 10) * pow(8, power)
        octal //= 10
        power += 1

    # Converting Decimal to Binary
    binary = 0
    digit_place = 1
    while decimal != 0:
        binary += (decimal % 2) * digit_place
        decimal //= 2
        digit_place *= 10

    return binary

# Sample Input
octal_number = 777

# Octal to Binary Conversion
binary_number = octal_to_binary(octal_number)

# Output
print(f"The binary equivalent of {octal_number} is {binary_number}")

C#

using System;

class Program {
    static int octal_to_binary(int octal) {
        // Converting Octal to Decimal
        int decimalNumber = 0;
        int power = 0;
        while (octal != 0) {
            decimalNumber += (octal % 10) * (int)Math.Pow(8, power);
            octal /= 10;
            power++;
        }

        // Converting Decimal to Binary
        int binaryNumber = 0;
        int digit_place = 1;
        while (decimalNumber != 0) {
            binaryNumber += (decimalNumber % 2) * digit_place;
            decimalNumber /= 2;
            digit_place *= 10;
        }

        return binaryNumber;
    }

    static void Main() {
        // Sample Input
        int octalNumber = 777;

        // Octal to Binary Conversion
        int binaryNumber = octal_to_binary(octalNumber);

        // Output
        Console.WriteLine(binaryNumber);
    }
}

Javascript

function octal_to_binary(octal)
{

    // Converting Octal to Decimal
    let decimal = 0;
    let power = 0;
    while (octal != 0) {
        decimal += (octal % 10) * Math.pow(8, power);
        octal = Math.floor(octal / 10);
        power++;
    }

    // Converting Decimal to Binary
    let binary = 0;
    let digit_place = 1;
    while (decimal != 0) {
        binary += (decimal % 2) * digit_place;
        decimal = Math.floor(decimal / 2);
        digit_place *= 10;
    }

    return binary;
}

// Sample Input
const octal_number = 777;

// Octal to Binary Conversion
const binary_number = octal_to_binary(octal_number);

// Output
console.log(`The binary equivalent of ${octal_number} is ${binary_number}`);

Output

The binary equivalent of 777 is 111111111

The time complexity: O(log n). Where n is the input octal number

The auxiliary space : O(1) .