[Programming] Question 21: Write a Program to Check if a number is an Armstrong number or not

 

#include <stdio.h>

int main() {
	int num, originalNum, remainder, result = 0, n = 0;

	printf("Enter an integer: ");
	scanf("%d", &num);

	originalNum = num;

	// store the number of digits of num in n
	while (originalNum != 0) {
		originalNum /= 10;
		++n;
	}

	originalNum = num;

	// check if the number is Armstrong
	while (originalNum != 0) {
		remainder = originalNum % 10;
		result += pow(remainder, n);
		originalNum /= 10;
	}

	if (result == num)
		printf("%d is an Armstrong number.\n", num);
	else
		printf("%d is not an Armstrong number.\n", num);

	return 0;
} 

Inside the main() function:

- Integer variables `num`, `originalNum`, `remainder`, `result`, and `n` are declared to store the input number, its original value, remainders, result after calculation, and number of digits respectively.

- The user is prompted to enter an integer.

- The number of digits of the input number is calculated and stored in `n`.

- Using a while loop, the sum of nth power of individual digits is calculated.

- If the calculated result is equal to the original number, it is an Armstrong number; otherwise, it is not.

- The program prints the result accordingly.