What is the difference between str_replace() and preg_replace() in PHP?

The main difference between str_replace() and preg_replace() in PHP is that str_replace() performs a simple text replacement based on exact matches, while preg_replace() allows for more advanced pattern matching using regular expressions. If you need to replace a simple string with another string, str_replace() is sufficient. However, if you need to perform more complex replacements based on patterns or conditions, preg_replace() is the better choice.

// Using str_replace() to replace a simple string
$text = "Hello, World!";
$new_text = str_replace("Hello", "Hi", $text);
echo $new_text;

// Using preg_replace() to replace based on a pattern
$text = "The quick brown fox jumps over the lazy dog.";
$new_text = preg_replace("/\b\w{4}\b/", "****", $text);
echo $new_text;