What are Armstrong numbers?

A positive integer number of n digits is called an Armstrong number of order n (order is a number of digits) if the sum of the power of n of each digit is equal to the number itself.

For example,

abcd... = pow(a,n) + pow(b,n) + pow(c,n) + pow(d,n) + ....

Common steps to find Armstrong Number in C programming:

• Enter any number
• Divide the given number into individual digits (For Example, Divide 153 into 1, 5, and 3) and count number digits (or find order).
• If the order is n, then calculate the power of n for each individual digits.
• Compare the original value with the sum value. If they are equal, then it is an Armstrong number. Otherwise, it is not an Armstrong Number in C.

C Program to find nth Armstrong number:

The mentioned C program find nth Armstrong Number in a given range. The minimum and maximum value of the range ask by users.

For example,

9th Armstrong Number  is 9
10th Armstrong Number is 153

#include<stdio.h>
#include <math.h>
int main()
{
    int rangeMinValue,rangeMaxValue;
    int count=1, n = 0;
    int i;
    printf("Please Enter the rangeMinValue = ");
    scanf("%d",&rangeMinValue);
    printf("Please Enter the rangeMaxValue = ");
    scanf("%d",&rangeMaxValue);
    printf("Please Enter the n to find nth Armstrong Number = ");
    scanf("%d",&n);
    for(i = rangeMinValue; i <= rangeMaxValue; i++)
    {
        int num=i, rem, digit=0, sum=0;
        //Copy the value for num in num
        num = i;
        // Find total digits in num
        digit = (int) log10(num) + 1;
        // Calculate sum of power of digits
        while(num > 0)
        {
            rem = num % 10;
            sum = sum + pow(rem,digit);
            num = num / 10;
        }
        // Check for Armstrong number
        if(i == sum)
        {
            if(count==n)
            {
                printf("%d\n",i);
                break;
            }
            else
            {
                count++;
            }
        }
    }
    return 0;
}

Output:

Please Enter the rangeMinValue = 1
Please Enter the rangeMaxValue = 1000
Please Enter the n to find nth Armstrong Number = 9
9