What best practices should be followed when implementing a word filter in PHP to avoid unintended matches like in the forum thread?

When implementing a word filter in PHP, it is important to use word boundaries (\b) to ensure that only whole words are matched and not substrings. This will prevent unintended matches like in the forum thread where "bad" matched "bathroom". Additionally, consider using an array of words to filter rather than a single string to avoid issues with word boundaries.

// List of words to filter
$badWords = array("bad", "inappropriate", "offensive");

// Input text to filter
$inputText = "This is a bad example of inappropriate language.";

// Loop through each word in the filter list
foreach($badWords as $word) {
    // Use word boundaries to match whole words only
    $inputText = preg_replace("/\b$word\b/i", "***", $inputText);
}

// Output filtered text
echo $inputText;