C++ Exercises: Find the sum of digits of a given number

Last update on April 07 2025 12:59:46 (UTC/GMT +8 hours)

10. Sum of the Digits of a Given Number

Write a program in C++ to find the sum of the digits of a given number.

Visual Presentation:

C++ Exercises: Find the sum of digits of a given number

Sample Solution :-

C++ Code :

#include <iostream> // Preprocessor directive to include the input/output stream header file

using namespace std; // Using the standard namespace to avoid writing std::

int main() // Start of the main function
{
    int num1, num2, r, sum = 0; // Declaration of integer variables 'num1', 'num2', 'r', and 'sum'

    // Display a message to find the sum of digits of a given number
    cout << "\n\n Find the sum of digits of a given number:\n";
    cout << "----------------------------------------------\n";

    // Prompt the user to input a number
    cout << " Input a number: ";
    cin >> num1; // Reading the number entered by the user

    num2 = num1; // Store the original number in 'num2' for displaying later

    // Loop to extract each digit and calculate their sum
    while (num1 > 0) 
    {
        r = num1 % 10; // Extract the rightmost digit of 'num1'
        num1 = num1 / 10; // Remove the rightmost digit from 'num1'
        sum = sum + r; // Add the extracted digit to the 'sum' variable
    }

    // Display the sum of digits of the original number 'num2'
    cout << " The sum of digits of " << num2 << " is: " << sum << endl;

    return 0; // Indicating successful completion of the program
}

Sample Output:

 Find the sum of digits of a given number:                             
----------------------------------------------                         
 Input a number: 1234                                                  
 The sum of digits of 1234 is: 10

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to compute the sum of digits of an input number using a while loop.
Write a C++ program that converts an integer to a string and sums its digits by iterating over the characters.
Write a C++ program to recursively calculate the sum of the digits of a given number.
Write a C++ program that extracts each digit from a number using modulus and division, and then prints their sum.

C++ Code Editor:

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