C++ Program For Octal To Decimal Conversion

In this article, we will discuss the C++ program for octal to decimal conversion with its explanation.

Program:

Here's a simple C++ program to convert an octal number to its decimal equivalent:

#include <iostream>
#include <cmath>
using namespace std;
int octalToDecimal(int octalNumber) {
int decimalNumber = 0, i = 0, remainder;
while (octalNumber != 0) {
remainder = octalNumber % 10;
decimalNumber += remainder * pow(8, i);
++i;
octalNumber /= 10;
}
return decimalNumber;
}
int main() {
int octalNumber;
cout << "Enter an octal number: ";
cin >> octalNumber;
int decimalNumber = octalToDecimal(octalNumber);
cout << "Decimal equivalent: " << decimalNumber << endl;
return 0;
}

Output:

Explanation:

1. Include Header Files:
Example
Copy
#include <iostream>
#include <cmath>
Try it Yourself

• ✅ #include <iostream>: This line includes the header file for the input/output stream, which is required to operate on input and output.
• ✅ #include <cmath>: This line includes the cmath header file, which is required to compute powers with the pow function.

1. namespace:
Example
Copy
using namespace std;
Try it Yourself

• ✅ As this line declares, the program will use the std namespace. The standard C++ library is contained in the std namespace.

1. Function for Octal to Decimal Conversion:
Example
Copy
int octalToDecimal(int octalNumber) {
int decimalNumber = 0, i = 0, remainder;
while (octalNumber != 0) {
remainder = octalNumber % 10;
decimalNumber += remainder * pow(8, i);
++i;
octalNumber /= 10;
}
return decimalNumber;
}
Try it Yourself

• ✅ An octal number is passed to the octalToDecimal function, which returns its decimal equivalent.
• ✅ It iterates through each digit of the octal number using a while loop.
• ✅ The modulo operator (%) is used inside the loop to calculate the remaining digit.
• ✅ The decimal equivalent is updated by multiplying the remainder by 8, raised to the power of i ( the digit's position).
• ✅ Until the octal number drops to zero, the loop is repeated.

1. Main Function:
Example
Copy
int main() {
int octalNumber;
cout << "Enter an octal number: ";
cin >> octalNumber;
int decimalNumber = octalToDecimal(octalNumber);
cout << "Decimal equivalent: " << decimalNumber << endl;
return 0;
}
Try it Yourself

• ✅ The program's entry point serves as the primary function.
• ✅ It declares a variable called octalNumber to store the octal number the user enters.
• ✅ Using cout and cin , the user is asked to enter an octal number.
• ✅ The user-inputted octal number is passed as an argument to the octalToDecimal function, and the outcome is saved in the decimalNumber
• ✅ After that, the user is shown the decimal equivalent via cout.

1. Return Statement:
Example
Copy
return 0;
Try it Yourself

The main function returns 0, indicating successful execution to the operating system.