C Program to Check a Number Is Armstrong Number or Not

An Armstrong number of three digits is an integer such that the sum of the cubes of its digits is equal to the number itself. For example,153  is an Armstrong number since 153=1*1*1+5*5*5+3*3*3

1. Using while and if-else:

#include<stdio.h>

main()  {

int num,sum=0,rem,arm;

printf("Enetr a number to check:");

scanf("%d",&num);

arm=num;

while(num!=0)

{     rem=num%10;

      sum=sum+(rem*rem*rem);

      num=num/10;

} if (arm==sum)

{     printf("Number is armstrong");

} else

{     printf("Number is not armstrong");

} }

Output:

2. Using Recursive Function:

#include<stdio.h>

main() {

  int armstrong(int num);

  int num,arm;

  printf("\n Enter a number: ");

  scanf("%d", &num);

 arm=armstrong(num);

 printf("\n %d is armstrong number",arm);

}  int armstrong(int num)

{

    int sum;

    if(num)  {

     sum=((num%10)*(num%10)*(num%10)) + armstrong(num/10)

 }  return sum;  }

Output: