C Program to Check Harshad Number

Posted in C Tutorial

Updated on Oct 06, 2024

By Mari Selvan

👁️ 56 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the realm of programming, a Harshad number (or Niven number) is a positive integer that is divisible by the sum of its digits. Checking for Harshad numbers involves finding the sum of the digits and determining if the original number is divisible by this sum.

In this tutorial, we will explore a C program designed to check whether a given number is a Harshad number.

📄 Example

Let's delve into the C code that accomplishes this task.

isHarshadNumber.c

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#include <stdio.h>

// Function to check if a number is a Harshad number
int isHarshadNumber(int number) {
  int originalNumber = number;
  int sumOfDigits = 0;

  // Calculate the sum of digits
  while (number > 0) {
    sumOfDigits += number % 10;
    number /= 10;
  }

  // If the original number is divisible by the sum of digits, it is a Harshad number
  return (originalNumber % sumOfDigits == 0);
}

// Driver program
int main() {
  // Replace this value with the number you want to check
  int number = 18;

  // Call the function to check if the number is a Harshad number
  if (isHarshadNumber(number)) {
    printf("%d is a Harshad number.\n", number);
  } else {
    printf("%d is not a Harshad number.\n", number);
  }

  return 0;
}

💻 Testing the Program

To test the program with different numbers, modify the value of number in the main program.

Output

18 is a Harshad number.

Compile and run the program to check if the specified number is a Harshad number.

🧠 How the Program Works

The program defines a function isHarshadNumber that takes an integer number as input and returns 1 (true) if the number is a Harshad number, and 0 (false) otherwise.
Inside the function, it calculates the sum of the digits by iterating through the digits of the number.
If the original number is divisible by the sum of digits, the function returns 1, indicating a Harshad number.
Inside the main program, replace the value of number with the desired number you want to check.
The program calls the isHarshadNumber function and prints the result.

📏 Between the Given Range

Let's delve into the C code that checks for Harshad numbers in the specified range.

isHarshad.c

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#include <stdio.h>

// Function to check if a number is Harshad
int isHarshad(int num) {
  int originalNum = num;
  int sum = 0;

  // Calculate the sum of digits
  while (num > 0) {
    sum += num % 10;
    num /= 10;
  }

  // Check if the number is Harshad
  return (originalNum % sum == 0);
}

// Driver program
int main() {
  printf("Harshad numbers in the range 1 to 20:\n");

  // Check Harshad numbers in the range
  for (int i = 1; i <= 20; ++i) {
    if (isHarshad(i)) {
      printf("%d ", i);
    }
  }

  printf("\n");

  return 0;
}

💻 Testing the Program

Output

Harshad numbers in the range 1 to 20:
1 2 3 4 5 6 7 8 9 10 12 18 20

Compile and run the program to see the Harshad numbers in the specified range.

🧠 How the Program Works

The program defines a function isHarshad that checks if a given number is a Harshad number.
Inside the function, it calculates the sum of the digits of the number.
It then checks if the original number is divisible by the sum of its digits.
The main function tests the Harshad numbers in the range from 1 to 20 and prints the results.

🧐 Understanding the Concept of Harshad Number

Before delving into the code, let's understand the concept of Harshad numbers. A Harshad number is a positive integer that is divisible by the sum of its digits.