revert_word.php

<?php


function revertWord($word)
{
    $length = strlen($word);
    for ($i = 0, $j = $length - 1; $i < ($length / 2); $i++, $j--) {
        $t = $word[$i];
        $word[$i] = $word[$j];
        $word[$j] = $t;
    }
    echo $word;
    echo "\n\n";
}

revertWord('hello my friend!');