What is the difference between using str_replace and preg_replace in PHP?

The main difference between using 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 complex pattern matching using regular expressions. If you need to do a basic string replacement, str_replace is sufficient. However, if you need to search for patterns or perform more advanced replacements, preg_replace is the better choice.

// Using str_replace for simple string replacement
$string = "Hello, World!";
$new_string = str_replace("Hello", "Hi", $string);
echo $new_string;

// Using preg_replace for pattern matching and replacement
$string = "The quick brown fox jumps over the lazy dog.";
$new_string = preg_replace("/\bfox\b/i", "cat", $string);
echo $new_string;