note 101938 added to function.preg-replace

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. ---- Server IP: 69.147.83.197 Probable Submitter: 217.19.30.100 ---- Manual Page -- http://www.php.net/manual/en/function.preg-replace.php Edit -- https://master.php.net/note/edit/101938 Del: integrated -- https://master.php.net/note/delete/101938/integrated Del: useless -- https://master.php.net/note/delete/101938/useless Del: bad code -- https://master.php.net/note/delete/101938/bad+code Del: spam -- https://master.php.net/note/delete/101938/spam Del: non-english -- https://master.php.net/note/delete/101938/non-english Del: in docs -- https://master.php.net/note/delete/101938/in+docs Del: other reasons-- https://master.php.net/note/delete/101938 Reject -- https://master.php.net/note/reject/101938 Search -- https://master.php.net/manage/user-notes.php