C Program to Check Whether a Number is Armstrong or Not

Write a c program to check whether a number is Armstrong or not. In this program, we take an input number from a user and check whether an input number is Armstrong or not.

Before we start solving this problem, let's understand what is Armstrong number?

What is Armstrong number?

An Armstrong number is an n-digit number that is equal to the sum of the nth powers of its digits.

For example - 153 , 371 is an Armstrong number.

Example 1 - 153 has 3 digits.

153 : 1 ³ + 5 ³ ;+ 3 ³ = 153

Example 2 - Take an example of 6 which has 1 digit.

6 : 6¹  = 6  It's an Armstrong number

Example 3 -  Take another example let's say 15, it has 2 digits.

15 : 1² + 5² = 26

So 15 is not an Armstrong number.

Example 4 - This time let's take bigger number 1634, it has 4 digits.

1634 : 1 ⁴ + 6 ⁴ + 3 ⁴ + 4 ⁴ = 1634

It's an Armstrong number.

We have understood the concept, let's solve this problem.

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C Program to Check Whether a Number is Armstrong or Not

In this example, we first take an input number. Then we find the length of a number and then calculate the sum of a number (Which i have explained in examples).  If entered number and the sum of a number is equal then it's an Armstrong number.

C program to calculate the sum of digits of a number

#include <stdio.h>
#include <math.h>

int main() {
 
  int num, remainder, temp, sum = 0, n = 0;
 
  //Take input number
  printf("Enter a number");
  scanf("%d", &num);
 
  temp = num;
 
  //Find the length of a number
  while(temp > 0) {
     n++;
     temp = temp/10;
  }
 
   
   //Again assign temp
   temp = num;
   
   while(temp > 0){
  
     remainder = temp % 10;
       
     sum  = sum + pow(remainder, n);
     temp = temp/10; 
   }
    
  
   if (num == sum){
      printf("\n %d is an Armstrong number ", num);
  
   } else {
     printf ("\n %d is not an Armstrong number ", num);
  
   }
    
   return 0;
}

Output -

Enter a number : 153

153 is an Armstrong number



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