How can special characters be handled in the delimiter parameter of preg_replace in PHP?

Special characters in the delimiter parameter of preg_replace can be handled by using a different delimiter that does not conflict with the special characters. This can be achieved by enclosing the delimiter in square brackets in the regex pattern. This ensures that the delimiter is treated as a literal character and not as a special character.

$original_string = "Hello, world!";
$pattern = '/,/';
$replacement = '-';
$modified_string = preg_replace('[' . $pattern . ']', $replacement, $original_string);
echo $modified_string; // Output: Hello- world!