How can PHP developers avoid including unwanted characters in extracted data when using preg_replace?

When using preg_replace in PHP to extract data, developers can avoid including unwanted characters by using the \w metacharacter, which matches any word character (alphanumeric characters and underscores). This ensures that only valid data is extracted without including unwanted characters like special symbols or punctuation marks.

// Example code snippet to extract only alphanumeric characters and underscores from a string
$data = "Hello, this is a string with special characters!123";
$extracted_data = preg_replace("/[^\w]/", "", $data);
echo $extracted_data; // Output: Hellothisisastringwithspecialcharacters123