swear_filter function for https://gist.github.com/lcherone/6f8043447f7f0099d430

gistfile1.php

<?php
/**
 * Swear word filtering function, requiers a list of words,
 * Second parameter reveals *n letters
 * 
 * @wordlist https://gist.github.com/lcherone/6f8043447f7f0099d430
 *
 * @param string $str
 * @param int $reveal
 * @return string
 */
function swear_filter($str, $reveal=null) {
	//load words
	$words = join("|", array_filter(array_map('preg_quote',array_map('trim', file('/path/to/badwords.txt')))));

	if($reveal !=null && is_numeric($reveal)){
		return preg_replace("/\b($words)\b/uie", '"".substr("$1",0,'.$reveal.').str_repeat("*",strlen("$1")-'.$reveal.').""', $str);
	}else{
		return preg_replace("/\b($words)\b/uie", '"".str_repeat("*",strlen("$1")).""', $str);
	}
}

echo swear_filter('Use your imagination.', 1);
?>