What are common challenges faced when using preg_replace with regular expressions in PHP?

One common challenge when using preg_replace with regular expressions in PHP is ensuring that the regex pattern is correctly formatted to match the desired text. Another challenge is handling special characters that may need to be escaped in the regex pattern. To solve these issues, it's important to thoroughly test the regex pattern and escape any special characters as needed.

$text = "Hello, World!";
$pattern = "/Hello,/";
$replacement = "Hi";

$new_text = preg_replace($pattern, $replacement, $text);
echo $new_text;