From: 7stud -- <bbxx789_05ss@...>
Date: 2007-10-28T09:28:57+09:00
Subject: Re: NOT reading an entire file into memory

Devi Web Development wrote:
> I have heard that File.readline is in fact equivalent to
> File.read.split('\n').each, which would really ruin my purpose of not
> loading the whole file. 
>

I doubt that is true, but as is often the case with Ruby there is no 
easily locatable documentation that describes File I/O buffering.  Just 
in case, here is another solution:

#create a data file containing:
#line 1
#line 2
#...
#line 10

File.open("data.txt", "w") do |file|
  10.times do |i|
    file.puts("line #{i+1}")
  end
end


#read lines 4-7 and display them:
File.open("data.txt") do |file|
  file.each_with_index do |line, i|
    i = i + 1   #i starts at 0

    if i < 4
      next
    elsif i < 8
      puts line
    else
      break
    end

  end
end
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