Question

How to check if a number is palindrome in Kotlin

Answer 1

fun reverseNumber(num: Int): Int {
    var rev = 0
    var number = num

    while (number > 0) {
        rev = rev * 10 + (number % 10)
        number /= 10
    }

    return rev
}

fun main() {
    val n = 12321

    if (reverseNumber(n) == n)
        println("Palindrome")
    else
        println("NOT Palindrome")
}


 
/*
run:

Palindrome
 
*/

 

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Answer 2

fun isPalindrome(number: Int): Boolean {
    fun reverseNumber(num: Int, rev: Int = 0): Int {
        return if (num == 0) rev else reverseNumber(num / 10, rev * 10 + num % 10)
    }
    
    return number == reverseNumber(number)
}

fun main() {
    val number = 12321
    
    println("Is $number a palindrome? ${isPalindrome(number)}")
}



 
/*
run:

Is 12321 a palindrome? true
 
*/

 

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