Armstrong Number in C Programming.

Theory

Armstrong number: An n-digit number equal to the sum of the n^th powers of its digits.

1. Raise each digit to a power equal to the number of digits in the number. 

     For instance, each digit of a four‑digit number would be raised to the fourth power; each digit of a five‑digit number would be raised to the fifth power; and so on.

2. Add the results.

3. If sum is equal to the number then it’s an Armstrong number.

Demonstrate this process for 1634—

         Because 1634 is a four-digit number, raise each digit to the fourth power, and add

1⁴ + 6⁴ + 3⁴ + 4⁴ = 1 + 1296 + 81 + 64 = 1634.

Hence 1634 is an Armstrong Number.

PROGRAM FOR ARMSTRONG NUMBER.

1.) Program for only 3 digit number

#include<stdio.h>

int main(){

    int num,r,sum=0,temp;

    printf("Enter a number: ");

    scanf("%d",&num);

    temp=num;

    while(num!=0){

         r=num%10;

         num=num/10;

         sum=sum+(r*r*r);

    }

    if(sum==temp)

         printf("%d is an Armstrong number",temp);

    else

         printf("%d is not an Armstrong number",temp);

    return 0;

}

Sample output:

Enter a number: 153

153 is an Armstrong number

2.) Program for any number of digits.

#include<stdio.h>

#include<Math.h>

#include<conio.h>

int main(){

    int num,r,t=0,sum=0,temp,count=0;

    printf("Enter a number: ");

    scanf("%d",&num);

    temp=num;

 while(temp>0){

  count++;

  temp = temp/10;

 }

 temp = num;

    while(num!=0){

         r=num%10;

         num=num/10;

    t=(int)pow((double) r, (double) count);

         sum=sum+t;

    }

    if(sum==temp)

         printf("%d is an Armstrong number",temp);

    else

         printf("%d is not an Armstrong number",temp);

 getch();

    return 0;

}

Sample output:

Enter a number: 1634

1634 is an Armstrong number