# Palindromic Number in Kotlin

Published on 07 October 2020 (Updated: 15 May 2023)

Welcome to the Palindromic Number in Kotlin page! Here, you'll find the source code for this program as well as a description of how the program works.

## Current Solution

``````fun main(args: Array<String>) {
var n: Int
var num: Int
var digit: Int
var rev: Int = 0

try {
num = args[0].toInt()

if (num >= 0){
n = num

do {
digit = num % 10
rev = (rev * 10) + digit
num = num / 10
}while (num != 0)

if (n == rev){
println(true)
}else{
println(false)
}
}else{
println("Usage: please input a non-negative integer")
}

}catch(e: Exception){
println("Usage: please input a non-negative integer")
}
}

``````

Palindromic Number in Kotlin was written by:

• Blake.Ke
• Isaac Anohene
• Jeremy Grifski

• Isaac Anohene
• Jeremy Grifski
• rzuckerm

If you see anything you'd like to change or update, please consider contributing.

## How to Implement the Solution

We first create some variables we will use in the algorithm in the `main` function as shown here:

``````fun main(args: Array<String>) {
var n: Int
var num: Int
var digit: Int
var rev: Int = 0
``````

Then we will convert the input argument from a string to an integer:

``````try {
num = args[0].toInt()

if (num >= 0){
...
}else{
println("Usage: please input a non-negative integer")
}

}catch(e: Exception){
println("Usage: please input a non-negative integer")
}
``````

If there is an error or the number is negative, we display the usage statement.

`````` Then we use a `do` while loop to reverse the number that was typed in:

```kotlin
do {
digit = num % 10
rev = (rev * 10) + digit
num = num / 10
}while (num != 0)
``````

Finally, we check if the number and its reverse are the same or not. If they are the same, we tell the user that it's true, otherwise we tell the user that it's false, as shown here:

``````if (n == rev){
println(true)
}else{
println(false)
}
``````

## How to Run the Solution

At this point, we probably want to actually run the Palindromic Number in Kotlin code snippet. Perhaps the easiest way to do so is to leverage the online Kotlin editor.

Alternatively, we can use the latest standalone compiler. Of course, we'll want to get a copy of Hello World in Kotlin while we're at it. With both in hand, all we need to do is navigate to the folder containing our files and run the following:

``````kotlinc hello-world.kt -include-runtime -d hello-world.jar
java -jar hello-world.jar
``````

The standalone Kotlin compiler compiles Kotlin down to a runnable Java Archive (`jar`) which we can then execute using the Java Runtime Environment.