Example: Binary to Base 9 Conversion in C++

// Binary to Base 9 Conversion
#include <iostream>
#include <cmath> // Required for pow function
#include <string> // Required for string manipulation if we build base 9 as a string
#include <algorithm> // Required for std::reverse

// Function to convert a binary number to its decimal equivalent
long long binaryToDecimal(long long binaryNum) {
    long long decimalNum = 0;
    long long base = 1; // Represents powers of 2 (2^0, 2^1, 2^2, ...)

    while (binaryNum > 0) {
        int lastDigit = binaryNum % 10; // Get the last digit of the binary number
        binaryNum /= 10; // Remove the last digit from the binary number
        decimalNum += lastDigit * base; // Add the product of digit and base (power of 2)
        base *= 2; // Move to the next power of 2
    }
    return decimalNum;
}

// Function to convert a decimal number to its base 9 equivalent
// Returns the base 9 number as a long long (e.g., 30 for 27 decimal)
long long decimalToBase9(long long decimalNum) {
    if (decimalNum == 0) return 0;

    std::string base9Str = ""; // To build the base 9 representation
    while (decimalNum > 0) {
        int remainder = decimalNum % 9; // Get the remainder when divided by 9
        base9Str += std::to_string(remainder); // Convert remainder to char and append
        decimalNum /= 9; // Divide decimal number by 9
    }
    std::reverse(base9Str.begin(), base9Str.end()); // Reverse the string to get correct order
    return std::stoll(base9Str); // Convert the string back to a long long
}

int main() {
    // Step 1: Declare variables for binary input
    long long binaryInput;

    // Step 2: Prompt user for binary number
    std::cout << "Enter a binary number: ";
    std::cin >> binaryInput;

    // Step 3: Convert binary to decimal
    long long decimalResult = binaryToDecimal(binaryInput);
    std::cout << "Decimal equivalent: " << decimalResult << std::endl;

    // Step 4: Convert decimal to base 9
    long long base9Result = decimalToBase9(decimalResult);
    std::cout << "Base 9 equivalent: " << base9Result << std::endl;

    return 0;
}