Sum of digits of a number using C

Problem Statement

In this program we will code a basic program to evaluate the sum of digits in C programming language.

Code

#include

int sumofdigits(int n)

{

 int sum=0,num=0;

 int rem=0;

 num=n;

 while(num>0)

 {

               rem=num%10;

               sum=sum+rem;

               num=num/10;

 }

 return sum;

}

int main()

{

  int n;

  printf("Enter the number ?\n");

  scanf("%d",&n);

  int res=sumofdigits(n);

  printf("Sum of digits : %d",res);

  return 0;

}

Output

Enter the number ? – 12345

Sum of digits : 15 

Explanation 

In this problem we have to find the sum of digits of a ‘n’th number.To do so we declare a variable ‘sum’,which will store the result value (don’t forget to initialize it with zero).

Let us consider an example :
Let the number be 23417 so our task is to evaluate 2+3+4+1+7. We can do so by finding the remainder of a number(adding it to sum),divide it with 10 until the number gets 0. For this we need a ‘while’ loop which will run till ‘N>0’.In each iteraion we perform three steps :

1.    rem=num%10; //rem=23417%10=7

2.    sum=sum+rem; //sum=7

3.    num=num/10; //num=23417/10=2341

Hence on repeating these steps(till n>0), we get the sum of digits of a number.