Reversing a String and Checking for Palindromes

In this lesson you will learn to reverse a string with mb_str_split and check for palindromes, while seeing how to handle multi-byte characters correctly. This is for anyone searching for "PHP reverse multibyte string".

To handle characters correctly - including accented letters and emoji - split the string into individual characters with mb_str_split() and reverse the order with array_reverse(). A string that reads the same forwards and backwards is called a palindrome.

The sample code splits the string character by character with mb_str_split($str), reverses the order with array_reverse(), and joins it back with implode('', ...). "racecar" comes out the same either way, so it is reported as a palindrome.

A common stumbling block for beginners is that plain str_split() does not split multi-byte characters correctly. Knowing the mb_ family of functions is essential background for any PHP application that handles non-ASCII text.

Unlike languages that treat a string as an array of characters, PHP expects you to reach for the dedicated multi-byte functions. Understanding that difference matters a great deal when building an international web service.

📖 Reference code

<?php
function isPalindrome($str) {
    $chars = mb_str_split($str);
    $reversed = implode('', array_reverse($chars));
    return $str === $reversed;
}

echo isPalindrome("racecar") ? "true" : "false";
echo "\n";
echo isPalindrome("hello") ? "true" : "false";

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🧪 This site can't compile or run PHP 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).