How to Convert Octal to Binary, Hexadecimal, Decimal, and String in Python and Other Popular Programming Languages

Introduction

Octal numbers are a base-8 numbering system often used in low-level programming, file permissions (especially in linux), and data encoding.

In this guide, you'll learn how to convert octal numbers into binary, hexadecimal, decimal, and string formats using Python, JavaScript, C#, Java, and C++ with easy, working examples.

If you want to skip the code and experiment instantly, try DevGizmo's Octal Converter - a free, browser-based tool that converts between octal, binary, hexadecimal, and decimal in real time.

Understanding Octal Numbers

The octal system (base-8) uses 0-7 digits. Each octal digit represents three binary bits.

Example:

Octal: 12  
Binary: 1010  
Decimal: 10

Converting Octal in Python

Python's int() and built-in formatting functions make base conversions simple.

Octal to Decimal

octal = "12"
decimal = int(octal, 8)
print(decimal)  # Output: 10

Octal to Binary

binary = bin(int(octal, 8))
print(binary)  # Output: 0b1010

Octal to Hexadecimal

hexadecimal = hex(int(octal, 8))
print(hexadecimal)  # Output: 0xa

Octal to String (Text)

octal_text = ["110", "145", "154", "154", "157"]  # 'Hello' in octal ASCII
string = ''.join(chr(int(oct_char, 8)) for oct_char in octal_text)
print(string)  # Output: Hello

Converting Octal in JavaScript

JavaScript's parseInt() and toString() handle base conversions easily.

Octal to Decimal

let octal = "12";
let decimal = parseInt(octal, 8);
console.log(decimal); // 10

Octal to Binary

let binary = parseInt(octal, 8).toString(2);
console.log(binary); // 1010

Octal to Hexadecimal

let hex = parseInt(octal, 8).toString(16);
console.log(hex); // a

Octal to String (Text)

function octalArrayToString(arr) {
  return arr.map(oct => String.fromCharCode(parseInt(oct, 8))).join('');
}

console.log(octalArrayToString(["110", "145", "154", "154", "157"])); // Hello

Converting Octal in C#

C#'s Convert.ToInt32() and ToString() make conversions simple.

Octal to Decimal

string octal = "12";
int decimalValue = Convert.ToInt32(octal, 8);
Console.WriteLine(decimalValue); // 10

Octal to Binary

string binary = Convert.ToString(Convert.ToInt32(octal, 8), 2);
Console.WriteLine(binary); // 1010

Octal to Hexadecimal

string hex = Convert.ToInt32(octal, 8).ToString("X");
Console.WriteLine(hex); // A

Octal to String (Text)

string[] octals = { "110", "145", "154", "154", "157" };
string text = string.Join("", octals.Select(o => (char)Convert.ToInt32(o, 8)));
Console.WriteLine(text); // Hello

Converting Octal in Java

Java provides Integer.parseInt() for base conversion and toString() for reformatting.

Octal to Decimal

String octal = "12";
int decimalValue = Integer.parseInt(octal, 8);
System.out.println(decimalValue); // 10

Octal to Binary

String binary = Integer.toBinaryString(Integer.parseInt(octal, 8));
System.out.println(binary); // 1010

Octal to Hexadecimal

String hex = Integer.toHexString(Integer.parseInt(octal, 8));
System.out.println(hex); // a

Octal to String (Text)

String[] octals = {"110", "145", "154", "154", "157"};
StringBuilder sb = new StringBuilder();

for (String oct : octals) {
    sb.append((char) Integer.parseInt(oct, 8));
}
System.out.println(sb.toString()); // Hello

Converting Octal in C++

C++ provides standard methods in std::stoul and std:stringstream.

Octal to Decimal

#include <iostream>
#include <string>

int main() {
    std::string octal = "12";
    unsigned long decimal = std::stoul(octal, nullptr, 8);
    std::cout << "Decimal: " << decimal << std::endl;
}

Octal to Binary

#include <iostream>
#include <bitset>
#include <string>

int main() {
    std::string octal = "12";
    unsigned long decimal = std::stoul(octal, nullptr, 8);
    std::bitset<16> binary(decimal);
    std::cout << "Binary: " << binary.to_string().substr(binary.to_string().find('1')) << std::endl;
}

Octal to Hexadecimal

#include <iostream>
#include <sstream>
#include <string>

int main() {
    std::string octal = "12";
    unsigned long decimal = std::stoul(octal, nullptr, 8);
    std::stringstream ss;
    ss << std::hex << std::uppercase << decimal;
    std::cout << "Hex: " << ss.str() << std::endl;
}

Octal to String (Text)

#include <iostream>
#include <string>
#include <vector>

int main() {
    std::vector<std::string> octals = {"110", "145", "154", "154", "157"};
    std::string text;
    for (const auto& oct : octals) {
        char ch = static_cast<char>(std::stoul(oct, nullptr, 8));
        text += ch;
    }
    std::cout << "String: " << text << std::endl;
}

When to Use Each Conversion

Octal to Binary: Bit-level visualisation and debugging

Octal to Decimal: Numeric calculations

Octal to Hexadecimal: Low-level data encoding

Octal to String (Text): ASCII or text interpretation

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Conclusion

Octal numbers bridge the gap between binary and human-readable representations. Understanding how to convert between octal, binary, decimal, and hexadecimal is essential for debugging, encoding, and system programming.

With these examples in Python, JavaScript, C#, Java, and C++, you can handle any octal conversions with confidence - or try DevGizmo's Octal Converter for instant results.

Summary

Learn to convert octan numbers into binary, hexadecimal, decimal, and string formats in Python, JavaScript, C#, Java, and C++. This detailed guide includes working code examples for each conversion and shows where each format is used. Try conversions instantly with DevGizmo's Octal Converter.