Armstrong Number Program In C

An armstrong number is a number which equal to the sum of the cubes of its individual digits. For example, 153 is an armstrong number as −

153 = (1)3 + (5)3 + (3)3
153 = 1 + 125 + 27
153 = 153

Algorithm

Algorithm of this program is very easy −

START
   Step 1 → Take integer variable Arms
   Step 2 → Assign value to the variable
   Step 3 → Split all digits of Arms
   Step 4 → Find cube-value of each digits
   Step 5 → Add all cube-values together
   Step 6 → Save the output to Sum variable
   Step 7 → If Sum equals to Arms print Armstrong Number
   Step 8 → If Sum not equals to Arms print Not Armstrong Number
STOP

Pseudocode

We can draft a pseudocode of the above algorithm as follows −

procedure armstrong : number
   
   check = number
   rem   = 0
   
   WHILE check IS NOT 0
      rem ← check modulo 10
      sum ← sum + (rem)3
      divide check by 10
   END WHILE
      
   IF sum equals to number
      PRINT armstrong
   ELSE
      PRINT not an armstrong
   END IF

end procedure

Implementation

Implementation of this algorithm is given below. You can change the value of arms variable and execute and check your program −

#include <stdio.h>

int main() {
   int arms = 153; 
   int check, rem, sum = 0;

   check = arms;

   while(check != 0) {
      rem = check % 10;
      sum = sum + (rem * rem * rem);
      check = check / 10;
   }

   if(sum == arms) 
      printf("%d is an armstrong number.", arms);
   else 
      printf("%d is not an armstrong number.", arms);
      
   return 0;
}

Output

Output of the program should be −

153 is an armstrong number.