Example: Octal to Decimal Converter in C++

// Octal to Decimal Converter
#include <iostream>
#include <cmath> // Not strictly necessary for this approach, but often used for powers

int main() {
    long long octalNumber;
    std::cout << "Enter an octal number: ";
    std::cin >> octalNumber;

    long long decimalNumber = 0;
    long long power = 1; // Corresponds to 8^0 initially

    // Step 1: Loop while the octal number is greater than 0
    while (octalNumber > 0) {
        // Step 2: Get the last digit of the octal number
        int lastDigit = octalNumber % 10;

        // Step 3: Check for invalid octal digit (must be 0-7)
        if (lastDigit >= 8) {
            std::cout << "Error: Invalid octal digit detected." << std::endl;
            return 1; // Exit with an error code
        }

        // Step 4: Multiply the last digit by the current power of 8 and add to decimal number
        decimalNumber += lastDigit * power;

        // Step 5: Update power to the next power of 8 (8^1, 8^2, etc.)
        power *= 8;

        // Step 6: Remove the last digit from the octal number
        octalNumber /= 10;
    }

    std::cout << "Decimal equivalent: " << decimalNumber << std::endl;

    return 0;
}