From: Josh Cheek <josh.cheek@...>
Date: 2010-01-31T01:41:00+09:00
Subject: Re: How do I use a variable in a regexp search string?

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On Fri, Jan 29, 2010 at 6:50 PM, joemac <joemacbusiness@gmail.com> wrote:

> Hi All,
>
> I dont know how to use a variable in a regex searchstring.
> ruby seems to only handle hardcoded serachstring in
> regex's.   How do you do this.   My code is below.
>
> Also - how do you put a variable name in a
> File.open("filename.txt") statement like this:
> File.open(filevariable) where filevariable can
> be set to anything?   I could not find this in
> the docs.
>
> Thanks, --Joe
> ================ snip code ===============
> #!/usr/bin/ruby
>
> F   = "filename.txt"
> searchstring = ARGV[0]
>
> print "searchstring is ", searchstring, "\n"
>
>
> File.open("filename.txt").each { |line|
> # this fails    puts line if line =~ searchstring
> # this fails    puts line if line =~ /searchstring/
> # this fails    puts line if line =~ "searchstring"
>
> #this works
> #    puts line
> }
>
>
This should work, here is an image showing how to use it:
http://tinypic.com/r/b5pi7m/6

filename = 'source.txt'
to_find  = Regexp.new ARGV[0]

puts "The Regexp is: #{to_find.inspect}"

File.open(filename).each do |line|
  if line =~ to_find
    puts "This line matches: #{line}"
    puts "This is what matches: #{line[to_find]}"
  end
end

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