From: Konrad Meyer <konrad@...>
Date: 2007-10-28T11:34:52+09:00
Subject: Re: NOT reading an entire file into memory

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Quoth 7stud --:
> 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.=20
> >
>=20
> I doubt that is true, but as is often the case with Ruby there is no=20
> easily locatable documentation that describes File I/O buffering.  Just=20
> in case, here is another solution:
>=20
> #create a data file containing:
> #line 1
> #line 2
> #...
> #line 10
>=20
> File.open("data.txt", "w") do |file|
>   10.times do |i|
>     file.puts("line #{i+1}")
>   end
> end
>=20
>=20
> #read lines 4-7 and display them:
> File.open("data.txt") do |file|
>   file.each_with_index do |line, i|
>     i =3D i + 1   #i starts at 0
>=20
>     if i < 4
>       next
>     elsif i < 8
>       puts line
>     else
>       break
>     end
>=20
>   end
> end

IO#each_with_index and IO#readline are probably the same internally, so the=
=20
real answer here is that NO, IO#readline is NOT the same as=20
=46ile.read.split('\n'), that's IO#readlines.

=2D-=20
Konrad Meyer <konrad@tylerc.org> http://konrad.sobertillnoon.com/

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