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Write a Kotlin Program to Print Armstrong Number Between Interval a and b, given a < b.

## What is Armstrong Number ?

A positive integer (x) of n digits is called armstrong number of order n (number of digits in x) if

abcd... = pow(a,n) + pow(b,n) + pow(c,n) + pow(d,n) + ....Note that abcd… is number x where a, b, c, d ….etc. are it’s digits. n is number of digits in x.

For example,

Input: a = 1 and b = 5 Output: 1 2 3 4 5

Input: a = 6 and b = 200 Output: 6 7 8 9 153

## 1. Program to Print Armstrong Number Between Interval

Sourcecode –

import java.util.* import kotlin.math.floor import kotlin.math.log10 import kotlin.math.pow import kotlin.math.roundToInt fun main() { val read = Scanner(System.`in`) println("Enter a:") val a = read.nextInt() println("Enter b:") val b = read.nextInt() if(a >= b) { println("Invalid interval") return } println("Armstrong number between $a and $b: ") for(i in a..b) { if(checkArmstrong((i))) { print("$i ") } } } private fun checkArmstrong(number: Int): Boolean { // Get the count of digits in number val n = floor(log10(number.toDouble()) + 1).roundToInt() var x = number // Find sum by power last digit in n to count. var sum = 0 while(x > 0) { val digit = x % 10 sum = (sum + (digit.toDouble().pow(n))).roundToInt() x /= 10 } // Return true if sum is equal to number return sum == number }

When you run the program, output will be –

Enter a: 1 Enter b: 5000 Armstrong number between 1 and 5000: 1 2 3 4 5 6 7 8 9 153 370 371 407 1634

###### Explanation:

Here, we have created an object of Scanner. Scanner takes an argument which says where to take input from.

**System.`in`** means take input from standard input – Keyboard.

**read.nextIn()** means read anything entered by user before space or line break from standard input – Keyboard.

Read the interval (a and b) entered by user and store it in variable **a** and **b**.

Then,

Run a loop from a to b.

Check for each value (i) if it is an armstrong number. If yes, print the value.

Thus, we went through Kotlin Program to Print Armstrong Number between interval a and b.

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