Reversing a String and Checking for Palindromes

In this lesson you will learn how to reverse a string in Kotlin and check whether it is a palindrome, covering the basics of string manipulation. This is for anyone searching for "Kotlin reverse string palindrome check".

.reversed() reverses a string. A string that reads the same forwards and backwards is called a palindrome.

The sample code writes isPalindrome() as an expression-bodied function (=) comparing the original with its reverse in the single line str == str.reversed(). "racecar" comes out the same either way, so it is reported as a palindrome.

A common stumbling block for beginners is the expression-bodied form itself. Defining a function with just = expression, with no braces and no return, is concise, idiomatic Kotlin that takes a moment to get used to.

You will rarely reverse a string in production, but as practice at working with text it is a classic learning exercise.

📖 Reference code

fun isPalindrome(str: String): Boolean = str == str.reversed()

fun main() {
    println(isPalindrome("racecar"))
    println(isPalindrome("hello"))
}

✍️ Your code

Type your code, then press "Run"

🧪 This site can't compile or run Kotlin directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser — nothing is sent anywhere).