Write a C program to calculate sum of digits using recursion

Recursion : :

• Recursion is the process of repeating items in a self-similar way. In programming languages, if a program allows you to call a function inside the same function, then it is called a recursive call of the function.

• The C programming language supports recursion, i.e., a function to call itself. But while using recursion, programmers need to be careful to define an exit condition from the function, otherwise it will go into an infinite loop.

• Recursive functions are very useful to solve many mathematical problems, such as calculating the factorial of a number, generating Fibonacci series, etc.

Here is the source code of the C program to calculate sum of digits using recursion. The C Program is successfully compiled and run on a Windows system. The program output is also shown below.

SOURCE CODE : :

/*  C program to calculate sum of digits using recursion  */

#include <stdio.h>

//function to calculate sum of all digits
int sumDigits(int num)
{
    static int sum=0;
    if(num>0)
    {
        sum+=(num%10); //add digit into sum
        sumDigits(num/10);
    }
    else
    {
        return sum;
    }
}
int main()
{
    int number,sum;

    printf("Enter any number :: ");
    scanf("%d",&number);

    sum=sumDigits(number);

    printf("\nSum of all digits of %d are :: %d\n",number,sum);

    return 0;
}

Output : : 

/*  C program to calculate sum of digits using recursion  */

Enter any number :: 123456

Sum of all digits of 123456 are :: 21

Process returned 0

Above is the source code for C program to calculate sum of digits using recursion which is successfully compiled and run on Windows System.The Output of the program is shown above .