program to find sum of digits of a number reducing into single digit code example

Example 1: Write a function digitsum that calculates the digit sum of an integer. The digit sum of an integer is the sum of all its digits.

function digSum(n) {
    let sum = 0;
    let str = n.toString();
    console.log(parseInt(str.substring(0, 1)));
    for (let i = 0; i < str.length; i++) {
        sum += parseInt(str.substring(i,i+1));
        
    }
    return sum;
}

Example 2: sum the digits of an integer

#include <stdio.h>
 
int getSum(unsigned long long n) {
    int sum = 0;
    for (; n; n /= 10)
    	sum += n % 10;
    return sum;
}

int main(){
	printf("Sum of digits = %d\n", getSum(555));
}