note 49362 added to function.preg-replace

note the that if you want to replace all backslashes in a string with double backslashes (like addslashes() does but just for backslashes and not quotes, etc), you'll need the following: $new = preg_replace('/\\\\/','\\\\\\\\',$old); note the pattern uses 4 backslashes and the replacement uses 8! the reason for 4 slashses in the pattern part has already been explained on this page, but nobody has yet mentioned the need for the same logic in the replacement part in which backslashes are also doubly parsed, once by PHP and once by the PCRE extension. so the eight slashes break down to four slashes sent to PCRE, then two slashes put in the final output. ---- Manual Page -- http://www.php.net/manual/en/function.preg-replace.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+49362 Delete: added to the manual -- http://master.php.net/manage/user-notes.php?action=delete+49362&report=yes&reason=added+to+the+manual Delete: bad code -- http://master.php.net/manage/user-notes.php?action=delete+49362&report=yes&reason=bad+code Delete: spam -- http://master.php.net/manage/user-notes.php?action=delete+49362&report=yes&reason=spam Delete: useless -- http://master.php.net/manage/user-notes.php?action=delete+49362&report=yes&reason=useless Delete: other reasons -- http://master.php.net/manage/user-notes.php?action=delete+49362&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+49362&report=yes Search -- http://master.php.net/manage/user-notes.php