How can one replace a specific word without replacing it if it is part of a larger word in PHP?

When replacing a specific word in a string in PHP, you can use the `str_replace()` function. However, if the word you want to replace is part of a larger word, you can use regular expressions with word boundaries `\b` to ensure you only replace the standalone word and not part of another word.

$string = "The quick brown fox jumps over the lazy dog";
$word_to_replace = "fox";
$new_word = "cat";

$result = preg_replace("/\b" . $word_to_replace . "\b/", $new_word, $string);
echo $result;