What are the differences between str_replace() and preg_replace() functions in PHP for string manipulation?

The main difference between str_replace() and preg_replace() functions 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 replace a specific string with another string, str_replace() is sufficient. However, if you need to perform more advanced string replacements based on patterns, preg_replace() is the better choice.

// Using str_replace() to replace a specific string
$string = "Hello, World!";
$new_string = str_replace("Hello", "Hi", $string);
echo $new_string;

// Using preg_replace() to replace based on a pattern
$string = "The quick brown fox jumps over the lazy dog.";
$new_string = preg_replace("/\b[bB]rown\b/", "red", $string);
echo $new_string;