I'm using this regex to get house number of a street adress.
[a-zA-ZßäöüÄÖÜ .]*(?=[0-9])
Usually, the street is something like "Ohmstraße 2a" or something. At regexpal.com my pattern matches, but I guess preg_replace() isn't identical with it's regex engine.
$num = preg_replace("/[a-zA-ZßäöüÄÖÜ .]*(?=[0-9])/", "", $num);
Update: It seems that my pattern matches, but I've got some encoding problems with the special chars like äöü
Update #2: Turns out to be a encoding problem with mysqli.