From: 7stud -- <bbxx789_05ss@...>
Date: 2009-08-15T16:03:07+09:00
Subject: Re: regexp issue on parsing from file

Alpha Blue wrote:
> Correction
> 
> counter = 1
> name_re = /(.*)\[(.*)\{/
> File.open("census.lua", "r") do |infile|
>   while (line = infile.gets)
>     if (line =~ name_re)
>       s_line = line.strip
>       c_line = s_line.size
>       right = c_line - 7
>       puts "#{counter}: #{s_line.slice!(2..right)}"
>       counter = counter + 1
>     end
>   end
> end

Ben's regex is better, and once you've done the matching, if your regex 
has a group around the desired information, you can retrieve the desired 
information--there is no need to slice and dice the string to extract 
the information:

count = 1

IO.foreach("data.txt") do |line|
   if md = /^\["(\w+?)"\]/.match(line)
     puts "#{count}: #{md[1]}"
     count += 1
   end
end

--output:--
1: Name
2: NameTwo

The term:

/^\["(\w+)"\]/.match(line)

returns a MatchData object if there is a match.  Otherwise, it returns 
nil.   That result is assigned to the variable md.  A MatchData object 
will evaluate to true.  So if a MatchData object is returned, i.e. there 
is a match, the if condition will evaluate to true, and the body of the 
if statement will execute.  Inside the if statement, you can ask the 
MatchData object for the match for the group in your regex.  md[0] is 
the whole match, md[1] is the match for group 1, md[2], is the match for 
group 2, etc.

The regexp says to look for the start of the string(^), then an opening 
bracket, then a double quote mark, then any character [a-zA-Z0-9] one or 
more times(+), then a quote mark, then a closing bracket.
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