Question

I want to highlight my keyword search text by using preg_replace in php but the problem is it won’t work with parentheses string ( and )

My function look like this…

$text_oritinal = "25 Hours: Colour In White (CD)";

function highlight($text_search, $text_original) {
  $str = preg_replace('#'. $text_search .'#i', '<span style="background-color:#FFFF66; color:#FF0000;">\\0</span>', $text_original);
  return $str;
}

Full original text is "25 Hours: Colour In White (CD)"

For example. If I use the keyword

$text_search = "25 Hours: Colour In White";

It return good replaced keyword with highlight background and text color.

<span style="background-color:#FFFF66; color:#FF0000;">25 Hours: Colour In White</span> (CD)

but! if I use this keyword included parentheses string ( and )

$text_search = "25 Hours: Colour In White (CD)";

It NOT return replaced background and text color.

I think it stuck with parentheses string ( and )

The question is how to highlight all text keyword matched without any problem with parentheses string ( and )?

Please share your idea. Thanks 🙂

Answer 1

You should call preg_quote:

function highlight($text_highlight, $text_search) {
  $str = preg_replace('#'. preg_quote($text_highlight) .'#i', '<span style="background-color:#FFFF66; color:#FF0000;">\\0</span>', $text_search);
  return $str;
}

Explanation:

Parenthesis are used to create submatches. Using them in your search string, will cause undesired results as they are reserved characters. You can prevent this, and other characters by using preg_quote which escapes regex reserved characters.