Adam W wrote: > Hello All, Hello,
> I'm using '-w' like any good hacker, but every time I try to use > backreferences in my regexps, I get a warning "\1 better written as $1 > at...." > > I'm confused because, according to perlretut: > "Although $1 and \1 represent the same thing, care should be taken > to use matched variables $1, $2, ... only outside a regexp and > backreferences \1, \2, ... only inside a regexp; not doing so may lead > to surprising and/or undefined results." > > The other source of relevant information seems to be here: > <http://www.perl.com/doc/manual/html/pod/perlre.html#WARNING_on_1_vs_1> > However, I'm having trouble understanding if it is referring to using > backreferences in general, or to a particular case where using \1 > instead of $1 is a bad idea. > > > Here is an example of one of my regexps that produces this warning: > $text =~ s!(.*?)(\()(.*?)(\))!<a\ href=\"\3\" alt=\"\3\">\1<\/a>!g; > > Should I be using $1 and $3 instead of \1 and \3 in this case, and if > so, why? The first part of s/// is a regular expression so you have to use \1, \2, \3, etc. however the second part of s/// is a double quoted string so it is preferred that you use $1, $2, $3, etc. because in a double quoted string the escape sequences \1, \2, \3, etc. are usually used as octal codes for characters. $ perl -le'print "\120\145\162\154"' Perl BTW, why capture $2 and $4 if you are not using them and why is everything backslashed? $text =~ s!(.*?)\((.*?)\)!<a href="$2" alt="$2">$1</a>!g; John -- use Perl; program fulfillment -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] <http://learn.perl.org/> <http://learn.perl.org/first-response>
