From: Robert Klemme <shortcutter@...>
Date: 2009-06-25T20:07:28+09:00
Subject: Re: regex that works on rubular.com but not in my program

2009/6/25 Andreas Hansen <hansenandr@gmail.com>
> i have some trouble with a regex.
> it works on rubular.com but not in my program
> ive used the content in testfile.txt on rubular.com
>
> the regex finds a ip-address, a flag and a username in a TCP-packet(an
> example: http://rubular.com/regexes/8389)
>
> regex =
> /(?:[I][P]\s)((?:[0-9A-Fa-f]{1,4}:){7}[0-9A-Fa-f]{1,4}|(?:\d{1,3}\.){3}\d{1,3}).{0,}(?:[:][\s])([P])(?:.{0,})$\s(?:^[E].{5}[@].{9}[Q])(?:.{30,42}\.)\W{0,}([\w\d]{1}(?:[\w\d-]+.){1,13}[\wA-Z0-9])/i

Ugh!  This is completely unreadable.  How about using switch /x and
embedding some comments?  Constructing the large regexp from a few
smaller expressions might also help.  For example, you could use
/[a-f0-9]/i for hex digits.

Few notes on glancing over this

[\wA-Z0-9] -> \w
\w includes characters and numbers

[\s] -> \s
[P] -> P
etc.

[\d\d]{1} -> \w


> filename = 'testfile.txt'
> file = File.open(filename).collect

Not closing the file descriptor properly...

> j = file.length
> i = 0
> while  i< j
>
>  a = file[i].to_s
>
>  b = a.scan(regex)
>  print b.length

You are not printing a newline here.  Are you maybe missing the print output?

>  i = i + 1
> end

You can greatly simplify your code to

File.foreach filename do |line|
  b = line.scan rx
  puts b.length
end

Kind regards

robert

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/