C++ Exercises: Compute the sum of the digits of an integer using function

Last update on August 14 2025 12:54:58 (UTC/GMT +8 hours)

84. Sum of the Digits of an Integer Using a Function

Write a C++ program to compute the sum of the digits of an integer using a function.

Visual Presentation:

C++ Exercises: Compute the sum of the digits of an integer using function

Sample Solution:-

C++ Code :

#include <iostream> // Including the input-output stream library
using namespace std; // Using standard namespace

// Function to calculate the sum of the digits of a number
int sumDigits(int num1, int n) 
{
    int sum = 0; // Initializing sum to zero
    while (num1 != 0) // Loop to sum the digits of the number
    {
        sum += num1 % 10; // Adding the last digit of 'num1' to 'sum'
        num1 /= 10; // Removing the last digit from 'num1'
    }
    return sum; // Returning the total sum of the digits
}

int main() // Main function
{
    int num1, sum, n; // Declaring three integer variables: num1, sum, n
    sum = 0; // Initializing the variable 'sum' to zero

    // Displaying a message to compute the sum of the digits of an integer
    cout << "\n\n Compute the sum of the digits of an integer:\n";
    cout << "-------------------------------------------------\n";

    // Asking the user to input any number
    cout << " Input any number: ";
    cin >> num1; // Taking user input for 'num1'
    n = num1; // Assigning the value of 'num1' to 'n' to preserve the original number

    // Displaying the sum of the digits of the original number using the function
    cout << " The sum of the digits of the number " << n << " is: " << sumDigits(num1, n) << endl;
}

Sample Output:

Compute the sum of the digits of an integer:                          
-------------------------------------------------                      
 Input any number: 255                                                 
 The sum of the digits of the number 255 is: 12

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program that defines a function to calculate the sum of digits of a number and calls it from main.
Write a C++ program to implement a recursive function that returns the sum of the digits of an input integer.
Write a C++ program that uses a separate function to compute and return the sum of the digits of a given number.
Write a C++ program to create a function that iterates through the digits of a number and returns their sum, then print the result.

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