Beefy Boxes and Bandwidth Generously Provided by pair Networks
more useful options
 
PerlMonks  

Re^2: pattern matching

by Athanasius (Monsignor)
on Oct 12, 2012 at 16:09 UTC ( #998735=note: print w/ replies, xml ) Need Help??


in reply to Re: pattern matching
in thread pattern matching

How about this?

#! perl use strict; use warnings; use YAPE::Regex::Explain; my $re = qr/(.)+/; print YAPE::Regex::Explain->new($re)->explain;

Output:

The regular expression: (?-imsx:(.)+) matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?-imsx: group, but do not capture (case-sensitive) (with ^ and $ matching normally) (with . not matching \n) (matching whitespace and # normally): ---------------------------------------------------------------------- ( group and capture to \1 (1 or more times (matching the most amount possible)): ---------------------------------------------------------------------- . any character except \n ---------------------------------------------------------------------- )+ end of \1 (NOTE: because you are using a quantifier on this capture, only the LAST repetition of the captured pattern will be stored in \1) ---------------------------------------------------------------------- ) end of grouping ----------------------------------------------------------------------

Not strictly documentation, but certainly confirmation that “Captures with quantifiers only return the last match.”

Update: Here is the official documentation:

/(\d)(\d)/ # Match two digits, capturing them into $1 and $2 /(\d+)/ # Match one or more digits, capturing them all into $1 /(\d)+/ # Match a digit one or more times, capturing the last into + $1

Note the difference between the second and third patterns. The second form is usually what you want. The third form does not create multiple variables for multiple digits. Parentheses are numbered when the pattern is compiled, not when it is matched.

The Camel Book, 4th edition, pages 221–222.

Athanasius <°(((><contra mundum


Comment on Re^2: pattern matching
Select or Download Code
Re^3: pattern matching
by perltux (Scribe) on Oct 12, 2012 at 16:12 UTC
    Thanks, I believe you are right, but how do I get then all matches as individual elements into the array?

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://998735]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others contemplating the Monastery: (7)
As of 2014-12-21 07:05 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    Is guessing a good strategy for surviving in the IT business?





    Results (104 votes), past polls