From: Robert Klemme <shortcutter@...>
Date: 2009-09-13T01:10:07+09:00
Subject: Re: Backtracking through a file

On 12.09.2009 17:57, M. Q. wrote:
> IO.gets steps through a file one line at a time. However, I cannot
> figure out how to (once i find something i need in the file) go
> backwards line by line through that file until i find something else. I
> thought possibly setting IO.lineno to the line before the current line
> that would work, but I think I just misunderstood what lineno was for.
> Anyone know a good way to do this?

One option is to create an Array of positions obtained via IO#tell while 
you go along.  Then you can move backwards to every line start. 
Something like

File.open "foo" do |io|
   idx = [io.tell]

   while l = io.gets
     p l
     idx << io.tell
   end
end

Cheers

	robert

-- 
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