C++ Exercises: Convert a octal number to decimal number

Last update on April 07 2025 12:59:16 (UTC/GMT +8 hours)

76. Octal to Decimal Conversion

Write a C++ program to convert an octal number to a decimal number.

Visual Presentation:

C++ Exercises: Convert a octal number to decimal number

Sample Solution:-

C++ Code :

#include <iostream> // Include input/output stream library
#include <math.h>   // Include math library for mathematical functions
using namespace std; // Use the standard namespace

int main() // Main function where the execution of the program starts
{
    long octal_num, decimal_num = 0; // Declare variables for octal and decimal numbers
    int i = 0; // Initialize an iteration variable

    cout << "\n\n Convert any octal number to decimal number:\n"; // Display message prompting for octal to decimal conversion
    cout << "----------------------------------------------------\n"; // Display separator line
    cout << " Input any octal number: "; // Prompt user to input an octal number
    cin >> octal_num; // Read the octal number input by the user

    // Loop to convert octal to decimal
    while (octal_num != 0) 
    {
        decimal_num = (long)(decimal_num + (octal_num % 10) * pow(8, i++)); // Calculate the decimal number using powers of 8
        octal_num = octal_num / 10; // Update the octal number by removing its last digit (rightmost digit)
    }

    cout << " The equivalent decimal number: " << decimal_num << "\n"; // Display the equivalent decimal number
}

Sample Output:

 Convert any octal number to decimal number:                           
----------------------------------------------------                   
 Input any octal number: 17                                            
 The equivalent decimal number: 15

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to convert an octal number to decimal by processing each digit with powers of 8.
Write a C++ program that reads an octal number and computes its decimal equivalent using a loop.
Write a C++ program to compute the decimal value of an octal input by multiplying each digit by 8 raised to the appropriate power.
Write a C++ program that converts an octal string to a decimal number by iterating through the string and summing weighted digits.

C++ Code Editor:

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