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;
    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");
        printf ("The given number is not a valid armstrong number\n");
    printf("Please Enetr Any Key To Continue");


  • 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.


I hope this post helps you understand Armstrong’s number and its implementation in the C programming language.

Keep coding 🙂

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