note 101938 deleted from function.preg-replace by crell

Note Submitter: nospam at probackup dot nl ---- Warning: a common made mistake in trying to remove all characters except numbers and letters from a string, is to use code with a regex similar to preg_replace('[^A-Za-z0-9_]', '', ...). The output goes in an unexpected direction in case your input contains two double quotes. echo preg_replace('[^A-Za-z0-9_]', '', 'D"usseldorfer H"auptstrasse') D"usseldorfer H"auptstrasse It is important to not forget a leading an trailing forward slash in the regex: echo preg_replace('/[^A-Za-z0-9_]/', '', 'D"usseldorfer H"auptstrasse') Dusseldorfer Hauptstrasse PS An alternative is to use preg_replace('/\W/', '', $t) for keeping all alpha numeric characters including underscores.