Preg_replace whole word only

[empiresolutions]

Im trying to make a naughty word filter. It removes bad words fine, but instances where there is a bad word found in the text like "assist" and "asses" get caught in the filter as well. Strangely though if the sentence is: My asses to assist me." the clean version will read: My asses to ***ist me." It seems to clear the first use of the word in another word, but then blocks the rest. Any ideas? My script is below. Thanks.

function cleanWords($value) {

	/*   strip naughty words   */
	$bad_word_file = 'standards/badwords.txt';
	$strtofile = fopen($bad_word_file, "r");
	$badwords = explode("\n", fread($strtofile, filesize($bad_word_file)));
	fclose($strtofile);
	
	for ($i = 0; $i < count($badwords); $i++) {
		$wordlist .= str_replace(chr(13),'',$badwords[$i]).'|';
	}
	$wordlist = substr($wordlist,0,-1);

	$value = preg_replace("/\b($wordlist)\b/ie", 'preg_replace("/./","*","\\1")', $value);	
	return $value;

}

[Atli]

Hey.

If you print the $wordlist, does it look right?
I tested this by just creating the $wordlist manually and it seemed to work fine.

[empiresolutions]

yes $wordlist is correct. If it helps the wordlist is just over a 1000 words.

[philipwayne]

Use the space character with or conditions.

(\s|^)(badword1 |badword2)(\s|$ )

That checks for either a space before the word or if it is at the start of the screen. Then checks for either a space or the end of the line.

[empiresolutions]

i ended up finding that the word "a.s.s." was in my list. I think the dots were messing up the expression. For thos interested, this is my new code. Thanks for any suggestions to get it where it is.

$_SESSION[wordlist] = join("|", array_map('trim', file('standards/badwords.txt')));

function cleanWords($value) {

	global $_SESSION;

	$value = preg_replace("/\b($_SESSION[wordlist])\b/ie", 'str_repeat("*", strlen("\\1")) ', $value);	
	return $value;

}

[Atli]

Hey.
Glad you got it working.

However, I would consider using a different method. - Putting the whole thing into the session is very inefficient. The list remains constant for every user, and rarely changes (if ever) right? - If so, then compiling it for every user like that and storing it in separate sessions for each one is just doing two things: eating up resources and cluttering the sessions with duplicate data.

You would be far better of compiling the regular expression into a common file, shared between all users. - This is how I would do this. (Wouldn't usually make a ready-to-use code example, but since you already solved this on your own...)
[code=php]<?php
define("BADWORD S_RAW_FILE", "/path/to/badwords.txt");
define("BADWORD S_EXP_FILE", "/path/to/badwords_expres sion.txt");

/**
* Returns a regular expression that can be used to check
* for "bad" words. Returns an expression in the format:
* - /\b(list|of|bad| words)\b/i
*/
function getBadWordsRege xp()
{
$regexp = "";

// Try to fetch an existing expression.
if(!file_exists (BADWORDS_EXP_F ILE) ||
filesize(BADWOR DS_EXP_FILE) <= 0 ||
($regexp = file_get_conten ts(BADWORDS_EXP _FILE)) === false)
{
// Make sure the raw word list exists
if(!file_exists (BADWORDS_RAW_F ILE)) {
trigger_error(" The bad words file does not exists.", E_USER_ERROR);
return false;
}

// Compile the regular expression
$regexp = '/\b(' . join("|", array_map('trim ', file(BADWORDS_R AW_FILE))) . ')\b/i';

// Try to save it
if(!is_writeabl e(BADWORDS_EXP_ FILE) ||
!file_put_conte nts(BADWORDS_EX P_FILE, $regexp))
{
trigger_error(" Could not save badwords expression. Check file permissions.", E_USER_WARNING) ;
}
}

// Return it
return $regexp;
}
?>[/code]

Then you could use it like:
[code=php]<?php
function cleanWords($val ue) {
$regexp = getBadWordsRege xp();
return preg_replace($r egexp . 'e', 'str_repeat("*" , strlen("\\1")) ', $value);
}
?>[/code]

P.S.
I have a couple of notes on your code, though.

• You don't need to import $_SESSION into functions using the global keyword. $_SESSION is a "super-global", which makes it available to you wherever you are in your code.
  
• All strings need to be quoted. That includes array keys. Which means that:
  [code=php]// This
  $_SESSION[wordlist];
  
  // Should be
  $_SESSION['wordlist'];[/code]
  If you leave it out, PHP assumes it is a constant. Failing to find a constant, it prints a warning and uses it as a string (which is why it works, even thought it is technically an error.) - For future-compatibility and performance reasons (minor as they may be), it is best to just remember the strings.

[empiresolutions]

thanks Atli! your suggestions are much appreciated.