Beefy Boxes and Bandwidth Generously Provided by pair Networks
laziness, impatience, and hubris
 
PerlMonks  

Re: Bug? Use of uninitialized value $1 in substitution iterator

by ikegami (Patriarch)
on Mar 04, 2009 at 15:28 UTC ( [id://748196]=note: print w/replies, xml ) Need Help??


in reply to Bug? Use of uninitialized value $1 in substitution iterator

Perl distinguishes between a capture that wasn't encountered in the match and a capture that matched zero characters.
use Data::Dumper qw( Dumper ); '' =~ / ^ ( (?: ( bb ) # $2 )? ) # $1 $ /x; local $Data::Dumper::Useqq = 1; local $Data::Dumper::Terse = 1; local $Data::Dumper::Indent = 0; print('$1 = ', Dumper($1), "\n"); print('$2 = ', Dumper($2), "\n");
$1 = "" $2 = undef

Replies are listed 'Best First'.
Re^2: Bug? Use of uninitialized value $1 in substitution iterator
by clinton (Priest) on Mar 04, 2009 at 18:29 UTC
    nicely explained

Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Node Status?
node history
Node Type: note [id://748196]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others pondering the Monastery: (5)
As of 2024-03-19 09:29 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found