I got this function:
preg_match("/öppet/iu", $string);
What if the "ö" is written as a html entity? Like this: ö or Ö Is there a way to find them as well?
Sure, just decode HTML entities before matching:
preg_match("/öppet/iu", html_entity_decode($string));
This has the benefit of working for other characters as well, e.g. if you want to match ä too at some point in the future.
You could do:
preg_match("/(?:ö|ö)ppet/iu", $string);
The ?: prevents the match from being captured to save memory, the | is "or"
If you are using a PHP version below 5.4.0 you have to specify the use of the UTF-8 encoding:
preg_match("/öppet/iu", html_entity_decode($string, ENT_COMPAT, 'UTF-8'));
Hope this will help.