C++ Program to Find Sum of Digits of a Number.

Example:

Input: num = 1432
Output: 10

Explanation: 1 + 4 + 3 + 2 = 10

Input: num = 9831
Output: 21

Explanation: 9 + 8 + 3 + 1 = 21

• Use a while loop to continuously extract the last digit of the number using the modulo operator (%).
• Add the extracted digit to a running total (sum), and then remove it from the number using the division (/) operator.
• This process continues until the number becomes zero.

//C++ Program to sum the digits of a number
#include <iostream>
using namespace std;

int main() {
    int num, sum = 0;
    cout << "Enter a number: ";
    cin >> num;

    while (num > 0) {
        sum += num % 10;
        num /= 10;
    }

    cout << "Sum of digits: " << sum << endl;
    return 0;
}

Enter a number: 1345
Sum of digits: 13

• Time Complexity: O(n)
• Space Complexity: O(1)

• Use a string stream to convert the integer number into a string. 
• Use a for loop to iterate over each character in the string and add its integer value (obtained by subtracting the ASCII value of the character '0') to a running total (sum).
• Print the value of the sum as an output.

//C++ code implementation for finding sum of diigts of a num
#include <iostream>
#include <sstream>

using namespace std;

int main() {
    int num, sum = 0;
    cout << "Enter a number: ";
    cin >> num;

    stringstream ss;
    ss << num;

    string str = ss.str();
    for (char c : str) {
        sum += c - '0';
    }

    cout << "Sum of digits: " << sum << endl;
    return 0;
}