Palindromic Number in Kotlin

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

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

Note: The solution shown above is the current solution in the Sample Programs repository as of Oct 11 2022 01:31:51. The solution was first committed on Oct 08 2020 16:44:11. As a result, documentation below may be outdated.

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.