# C program to check whether a number is an Armstrong number or not

C program to check whether a number is an Armstrong number or not checks if a given number is an Armstrong number or not. An Armstrong number is a number that is equal to the sum of the nth power of each digit in the number.

For example, 153 is an Armstrong number because 1^3 + 5^3 + 3^3 = 153. The c program first prompts the user to enter a number,

then counts the number of digits in the number and calculates the sum of the nth power of each digit. If the calculated sum is equal to the entered number, the program outputs that the number is an Armstrong number, otherwise, it outputs that the number is not an Armstrong number.

• The program first declares several integer variables – num, originalNum, remainder, result, and n.
• It prompts the user to enter an integer using the `printf` and `scanf` functions.
• The program then counts the number of digits in the entered integer by dividing it by 10 repeatedly in a `while` loop and incrementing the value of `n`.
• The program then calculates the sum of the nth power of each digit of the entered integer in a `while` loop using the `pow()` function from the `math.h` library.
• If the calculated sum is equal to the entered integer, the program outputs that the number is an Armstrong number. Otherwise, it outputs that the number is not an Armstrong number.
``````#include <stdio.h>
#include <math.h>

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

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

originalNum = num;

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

originalNum = num;

// calculate sum of nth power of each digit
while (originalNum != 0) {
remainder = originalNum % 10;
result += pow(remainder, n);
originalNum /= 10;
}

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

return 0;
}``````

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