Example: Sum of Digits - Recursive Method in C++

C
C++
C#
Java
Python
PHP
// Sum of Digits - Recursive Method
#include <iostream>
using namespace std;

// Recursive function to calculate sum of digits
int sumDigitsRecursive(int n) {
    // Base Case: If number is 0, sum is 0
    if (n == 0) {
        return 0;
    }
    // Recursive Step: Add the last digit to the sum of the remaining digits
    return (n % 10) + sumDigitsRecursive(n / 10);
}

int main() {
    int number;
    
    // Step 1: Prompt user for input
    cout << "Enter an integer number: ";
    cin >> number;

    // Step 2: Handle negative numbers by taking absolute value before calling recursive function
    int absoluteNumber = number;
    if (absoluteNumber < 0) {
        absoluteNumber = -absoluteNumber;
    }

    // Step 3: Call the recursive function
    int sum = sumDigitsRecursive(absoluteNumber);

    // Step 4: Display the result
    cout << "The sum of the digits of " << number << " is: " << sum << endl;
    
    return 0;
}