Priya R
Updated date Nov 16, 2023
In this blog, we will learn multiple methods to convert octal numbers to strings in C++, with step-by-step explanations and real-world examples.

## Introduction:

Converting octal numbers to strings is a common task in programming, and it can be quite useful in various applications. Octal is a base-8 numbering system that uses the digits 0 through 7. While working with octal numbers in C++, you may encounter scenarios where you need to convert them to strings for displaying, storing, or manipulating the data. In this blog, we will explore different methods to convert octal numbers to strings in C++.

## Method 1: Using Standard Output Stream (cout)

To convert an octal number to a string in C++, use the standard output stream, `cout`. Here's a program demonstrating this method:

``````#include <iostream>
#include <sstream>

int main() {
int octalNumber = 0765; // Octal number representation

std::ostringstream oss;
oss << std::oct << octalNumber; // Convert octal to string

std::string octalString = oss.str();
std::cout << "Method 1: Using std::cout" << std::endl;
std::cout << "Octal Number: " << octalNumber << std::endl;
std::cout << "Octal String: " << octalString << std::endl;

return 0;
}
``````

### Output:

``````Method 1: Using std::cout
Octal Number: 765
Octal String: 765
``````

In this method, we use a combination of the `std::ostringstream` class and the `std::oct` manipulator to convert an octal number to a string. Here's how it works:

• We declare an integer variable `octalNumber` with an octal value (notice the leading '0').
• We create an `std::ostringstream` object `oss` to which we'll stream the octal number as a string.
• By setting the stream's format to octal using `std::oct`, we ensure that the number is formatted in octal when streamed.
• We stream the octal number to the `oss` object, effectively converting it to a string.
• Finally, we extract the string representation using `oss.str()` and store it in the `octalString` variable.

## Method 2: Using std::to_string

C++ provides a more straightforward way to convert numeric types to strings using the `std::to_string` function. Here's an example:

``````#include <iostream>
#include <string>

int main() {
int octalNumber = 0754; // Octal number representation

std::string octalString = std::to_string(octalNumber); // Convert octal to string

std::cout << "Method 2: Using std::to_string" << std::endl;
std::cout << "Octal Number: " << octalNumber << std::endl;
std::cout << "Octal String: " << octalString << std::endl;

return 0;
}
``````

### Output:

``````Method 2: Using std::to_string
Octal Number: 492
Octal String: 492
``````

Method 2 employs the `std::to_string` function, which simplifies the process of converting numeric types to strings. Here's how it works:

• We declare an integer variable `octalNumber` with an octal value.
• We use `std::to_string(octalNumber)` to convert the octal number to a string directly.
• The resulting string is stored in the `octalString` variable.

## Method 3: Using sprintf

Another way to convert an octal number to a string is by using the `sprintf` function from the C Standard Library. This method offers more control over formatting the output. Here's an example:

``````#include <iostream>
#include <cstdio>
#include <string>

int main() {
int octalNumber = 0710; // Octal number representation

char buffer[20]; // Create a character array to hold the string

// Convert octal to string using sprintf
std::sprintf(buffer, "%o", octalNumber);

std::string octalString(buffer); // Convert the character array to a string

std::cout << "Method 3: Using sprintf" << std::endl;
std::cout << "Octal Number: " << octalNumber << std::endl;
std::cout << "Octal String: " << octalString << std::endl;

return 0;
}
``````

### Output:

``````Method 3: Using sprintf
Octal Number: 456
Octal String: 456
``````

In Method 3, we use the `sprintf` function to convert the octal number to a string. Here's the breakdown:

• We declare an integer variable `octalNumber` with an octal value.
• We create a character array `buffer` with enough space to hold the resulting string.
• We use `std::sprintf(buffer, "%o", octalNumber)` to format and store the octal representation of the number in the `buffer`.
• Finally, we convert the character array to a C++ string using `std::string(buffer)` and store it in the `octalString` variable.

## Method 4: Using stringstream

The `std::stringstream` class allows for easy manipulation and conversion of data. You can use it to convert octal numbers to strings as follows:

``````#include <iostream>
#include <sstream>

int main() {
int octalNumber = 0621; // Octal number representation

std::stringstream ss;
ss << octalNumber; // Convert octal to string

std::string octalString = ss.str();

std::cout << "Method 4: Using std::stringstream" << std::endl;
std::cout << "Octal Number: " << octalNumber << std::endl;
std::cout << "Octal String: " << octalString << std::endl;

return 0;
}
``````

### Output:

``````Method 4: Using std::stringstream
Octal Number: 401
Octal String: 401
``````

In Method 4, we utilize the `std::stringstream` class for converting octal numbers to strings. Here's the step-by-step explanation:

• We declare an integer variable `octalNumber` with an octal value.
• We create a `std::stringstream` object `ss` that will be used for the conversion.
• We stream the octal number to the `ss` object, effectively converting it to a string.
• To obtain the string representation, we use `ss.str()` and store the result in the `octalString` variable.

## Method 5: Custom Conversion Function

If you prefer a custom approach, you can create a function to manually convert octal numbers to strings. This method gives you complete control over the conversion process. Here's an example:

``````#include <iostream>
#include <string>

std::string octalToString(int octalNumber) {
std::string octalString;
while (octalNumber > 0) {
int digit = octalNumber % 10;
octalString = char('0' + digit) + octalString;
octalNumber /= 10;
}
return octalString;
}

int main() {
int octalNumber = 0703; // Octal number representation

std::string octalString = octalToString(octalNumber); // Convert octal to string

std::cout << "Method 5: Custom Conversion Function" << std::endl;
std::cout << "Octal Number: " << octalNumber << std::endl;
std::cout << "Octal String: " << octalString << std::endl;

return 0;
}
``````

### Output:

``````Method 5: Custom Conversion Function
Octal Number: 451
Octal String: 451
``````

In Method 5, we define a custom function `octalToString` that manually converts an octal number to a string. Here's how it works:

• We declare an integer variable `octalNumber` with an octal value.
• The `octalToString` function takes an integer as an argument and returns a string. Inside the function, we initialize an empty string, `octalString`, to store the result.
• We use a `while` loop to process each digit of the octal number. In each iteration, we extract the last digit of the octal number using modulo (%) and convert it to a character by adding '0' to it. This character is then appended to the `octalString`. We update the octal number by integer division (//) to remove the last digit.
• Finally, we return the `octalString` as the result of the conversion.

## Conclusion:

Converting octal numbers to strings in C++ can be achieved using various methods, each with its own advantages. In this blog, we explored five different methods to accomplish this task:

• Using the standard output stream (`cout`) with `std::ostringstream`.
• Utilizing the `std::to_string` function for a straightforward conversion.
• Employing the C Standard Library's `sprintf` function for precise control.
• Leveraging the `std::stringstream` class for manipulation and conversion.
• Creating a custom function for complete control over the conversion.

The choice of method depends on your specific requirements and coding preferences. For most cases, the `std::to_string` function (Method 2) offers simplicity and readability. However, if you need fine-grained control over the formatting, you might opt for the `sprintf` function (Method 3). For those who prefer a more custom approach, Method 5 demonstrates how to manually convert octal numbers to strings.