Sum of Digits of a Number in C Program using For loop | While | Do-While loop | Function | Recursion

Sum of digits of a number in c program.

In this article, you will learn how to make the sum of digits of a number in c by using various approaches like: for loop, while loop, do-while loop, function, and recursion.

Example-1

Example-2

You should know about the following topics in C programming to understand this program:

• For loop in C
• While loop in C
• Do-while loop in C
• C Function
• C Recursion

1 - Sum of Digits of a Number in C using For loop

// Sum of Digits of a Number in C using For loop
#include <stdio.h>

// It's the main function of the program
int main()
{
    int num, sum = 0, mod;

    // Step-1 Enter a Number
    printf("Enter Number: ");
    scanf("%d", &num);

    // Step-2 Iterate over the input number to get each digit and make the sum of each digit
    for (int n = num; n > 0; n = n / 10)
    {
        mod = n % 10;
        sum += mod;
    }

    // Step-3 Final output of the program
    printf("\nOutput: %d", sum);
    return 0;
}

Run

Output

2 - Sum of Digits of a Number in C using While loop

// Sum of Digits of a Number in C using While loop
#include <stdio.h>

// It's the main function of the program
int main()
{
    int num, sum = 0, mod;

    // Step-1 Enter a Number
    printf("Enter Number: ");
    scanf("%d", &num);

    // Step-2 Iterate over the input number to get each digit and make the sum of each digit
    while (num > 0)
    {
        mod = num % 10;
        sum += mod;
        num = num / 10;
    }

    // Step-3 Final output of the program
    printf("\nOutput: %d", sum);
    return 0;
}

Run

3 - Sum of Digits of a Number in C using Do-While loop

// Sum of Digits of a Number in C using Do-While loop
#include <stdio.h>

// It's the main function of the program
int main()
{
    int num, sum = 0, mod;

    // Step-1 Enter a Number
    printf("Enter Number: ");
    scanf("%d", &num);

    // Step-2 Iterate over the input number to get each digit and make the sum of each digit
    do
    {
        mod = num % 10;
        sum += mod;
        num = num / 10;
    } while (num > 0);

    // Step-3 Final output of the program
    printf("\nOutput: %d", sum);
    return 0;
}

Run

Output

4 - Sum of Digits of a Number in C using Function

// Sum of Digits of a Number in C using Function
#include <stdio.h>

// Function to make sum of each digits
int sum_of_digits(int num)
{
    int sum = 0, mod;

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

// It's the main function of the program
int main()
{
    int num;

    // Step-1 Enter a Number
    printf("Enter Number: ");
    scanf("%d", &num);

    // Step-2 Call the sum_of_digits() function to get the sum of each digits
    // & print the final output of the program
    printf("\nOutput: %d", sum_of_digits(num));

    return 0;
}

Run

5 - Sum of Digits of a Number in C using Recursion

// Sum of Digits of a Number in C using Recursion
#include <stdio.h>

// Recursive function to make the sum of each digit
int rec_sum_digits(int num, int sum, int mod)
{
    mod = num % 10;
    sum += mod;
    num = num / 10;
    if (num > 0)
        rec_sum_digits(num, sum, mod);
    else
        return sum;
}

// It's the main function of the program
int main()
{
    int num, sum = 0, mod = 0;

    // Step-1 Enter a Number
    printf("Enter Number: ");
    scanf("%d", &num);

    // Step-2 Call the recursive function rec_sum_digits() to get the sum of each digits
    printf("\nOutput: %d", rec_sum_digits(num, sum, mod));
    return 0;
}

Run

Output