Re: RegExp question: how to add a number?

On 15 October 2010 10:16, Ford, Mike <M.Ford@leedsmet.ac.uk> wrote: >> -----Original Message----- >> From: Andre Polykanine [mailto:andre@oire.org] >> Sent: 14 October 2010 21:42 >> >> Hi everyone, >> I hope you're doing well (haven't written here for a long time :-)). >> The question is as follows: I have a regexp that would do the >> following. If the string begins with "Re:", it will change the >> beginning to "Re[2]:"; if it doesn't, then it would add "Re:" at >> the >> beginning. But (attention, here it is!) if the string starts with >> something like "Re[4]:", it should replace it by "Re[5]:". >> Here's the code: >> >> $start=mb_strtolower(mb_substr($f['Subject'], 0, 3)); >> if ($start=="re:") { >> $subject=preg_replace("/^re:(.+?)$/usi", "re[2]:$1", >> $f['Subject']); >> } elseif ($start=="re[") { >> // Here $1+1 doesn't work, it returns "Re[4+1]:"! >> $subject=preg_replace("/^re\[(\d+)\]:(.+?)$/usi", "re[$1+1]:$2", >> $f['Subject']); >> } else { >> $subject="Re: ".$f['Subject']; >> } >> >> I know there actually exists a way to do the numeral addition >> ("Re[5]:", not "Re[4+1]:"). >> How do I manage to do this? > > This looks like a job for the "e" modifier (see > http://php.net/manual/en/reference.pcre.pattern.modifiers.php, and > example #4 at http://php.net/preg_replace). Something like: > >  $subject = preg_replace("/^re\[(\d+)\:](.+?)$/eusi", > "'re['.(\\1+1).']:\\2'", $f['Subject']); > > Cheers! > > Mike Watch out for the missing '[1]'. This needs to become '[2]' and not '[1]'. The callback seems to be the only way I could get the regex to work. -- Richard Quadling Twitter : EE : Zend @RQuadling : e-e.com/M_248814.html : bit.ly/9O8vFY