Using str_replace to Match Whole Word

[schwing]

I'm trying to use str_replace to match whole words, but have only been able to match just the string, even if it's part of the word.

To just to see it match, I used this code:

$tmpstring = str_replace($db_term , strtoupper($db_term) , $tmpstring);

For instance, if the db_term is "aft" then it finds "after" and replaces it with "AFTer".

I've even tried this bit of code:
$tmpstring = preg_replace("/($db_term)/i" , "<font color=red>" . $db_term ."</font>" , $tmpstring);

Same thing.

Any ideas?

[schwing]

Here's what worked:

$tmpstring = preg_replace("/(\b($db_term)\b)/i" , "<font color=red>" . '\2' ."</font>" , $tmpstring);

The \b indicate "word boundaries" and the '\2' references the matched $db_term.

Hope this helps somebody who's struggling with regex. 🙂