PHP | wrap the last word of a string in span

last_word_wrap.php

<?php
// Function to wrap last word in span
function last_word_wrap($string, $class = null) {
    $span = '<span';
    if( $class ) {
        $span .= ' class="' . $class . '"';
    }
    $span .= '>';
    $wrapped = preg_replace('/\s(\S*)$/', ' ' . $span . '$1', $string);
    $wrapped .= '</span>';
    return $wrapped;
}

Here's my try:

<?php
/**
 * Wrap last word with span
 * @author: Elron
 * https://stackoverflow.com/questions/18612872/get-the-last-word-of-a-string
 */
function wrap_last_word($string) {
    // Breaks string to pieces
    $pieces = explode(" ", $string);

    // Modifies the last word
    $pieces[count($pieces)-1] = '<span class="is-last-word">' . $pieces[count($pieces)-1] . '</span>';

    // Returns the glued pieces
    return implode(" ", $pieces);
}

wrap_last_word('hello this is wrapped');
// returns this:
// hello this is <span class="is-last-word">wrapped</span>

That's much neater @elron, thank you! preg_replace always looks messy.

Thanks!
I wonder if there any performance advantage for preg_replace or explode/implode.
Anyway, I'm using it for short strings so it should be fine.