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

Last update on August 14 2025 12:54:57 (UTC/GMT +8 hours)

83. Sum of the Digits of an Integer

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

Visual Presentation:

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

Sample Solution:-

C++ Code :

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

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

    // Loop to compute the sum of the digits of the input number
    while (num1 != 0) 
    {
        sum += num1 % 10; // Adding the last digit of 'num1' to 'sum'
        num1 /= 10; // Removing the last digit from 'num1'
    }

    // Displaying the sum of the digits of the original number
    cout << " The sum of the digits of the number " << n << " is: " << sum << endl;  
}

Sample Output:

 Compute the sum of the digits of an integer:                          
-------------------------------------------------                      
 Input any number: 25                                                  
 The sum of the digits of the number 25 is: 7

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to compute the sum of all digits in a given integer using a while loop.
Write a C++ program that reads a number and calculates the sum of its digits by repeatedly extracting the last digit.
Write a C++ program to sum the digits of an integer recursively and print the final result.
Write a C++ program that converts an integer to a string and iterates over each character to sum its numeric value.

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