What are the potential pitfalls of using str_replace() to search for words in a PHP string?

Using str_replace() to search for words in a PHP string may replace partial matches or unintended occurrences of the word. To avoid this issue, you can use the preg_replace() function with word boundaries (\b) to ensure that only whole words are replaced.

// Original string
$string = "The quick brown fox jumps over the lazy dog";

// Word to search for
$word = "fox";

// Replace whole word using preg_replace
$new_string = preg_replace("/\b$word\b/", "cat", $string);

// Output the new string
echo $new_string;