Program to Check if a Number is a Harshad Number in C

Harshad Number

A Harshad number (also called a Niven number) is a number that is divisible by the sum of its digits. For example, 18 is a Harshad number because 1 + 8 = 9 and 18 is divisible by 9.

We will explore a method to check if a given number is a Harshad number using C programming.

Method: Using a while Loop

We extract each digit, sum them up, and check if the original number is divisible by this sum.

#include <stdio.h>

int isHarshad(int num) {
    int originalNum = num, sum = 0, digit;
    
    // Calculate the sum of digits
    while (num > 0) {
        digit = num % 10;
        sum += digit;
        num /= 10;
    }
    
    return (originalNum % sum == 0);
}

int main() {
    int num;
    printf("Enter a number: ");
    scanf("%d", &num);
    
    if (isHarshad(num))
        printf("%d is a Harshad number", num);
    else
        printf("%d is not a Harshad number", num);
    
    return 0;
}
            

Output:

Enter a number: 18
18 is a Harshad number