How to Check Armstrong Number in C Language

In this article, we will write a C language program to check whether a given number is Armstrong number or not.

What is an Armstrong Number?

An Armstrong number is n digit number that sum of its individual digit’s power n equals that number. For example, 370 is an Armstrong number because: (3)^3 + (7)^3 + (0)^3 = 370

Here we have taken power 3 because the number 370 is 3 digit number. If we take a 4 digits number of new power will be 4 to calculate. For example, the power for the number 1667 will be 4.

Read Also: Download and Install Turbo C++ for Windows 10 (Full Installation Guide)

C Program to Check Armstrong Number

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

void main()
{
    int number, sum = 0, rem = 0, power = 0, temp, len_temp, len = 0;

    printf ("Enter a number to check armstrong number: ");
    scanf("%d", &number);
    temp = number;
    len_temp = temp;
    while (len_temp != 0){
        len_temp /= 10;
        len++;
    }
    while (number != 0){
        rem = number % 10;
        power = pow(rem, len);
        sum = sum + power;
        number = number / 10;
    }
    if (sum == temp)
        printf ("The given number is a valid armstrong number\n");
    else
        printf ("The given number is not a valid armstrong number\n");
    printf("Please Enetr Any Key To Continue");
    getch();
    clrscr();
}

Explanation

First, we get an integer number from the user and store it to the number variable.
Next, we count the length of that number.
After that, we create a while loop to find the sum of each individual’s power bit in the given number.
At last, we compare the sum with the given number and print the output.

This program works for a range of 1 to 1000. You can even explore more by taking a big integer.