From: Matt Brown <matt.g.brown@...>
Date: 2006-06-07T10:44:37+09:00
Subject: Re: What's going on here? (Newbie question)

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Exactly what I was looking for, thank you.

On 6/6/06, Mike Stok <mike@stok.ca> wrote:
>
>
> On 6-Jun-06, at 9:36 PM, MB wrote:
>
> > In irb:
> >
> > f = File.new('numbers.txt')
> > => #<File:numbers.txt>
> >
> > f.each {|line| puts line}
> > 123
> > 456
> > 789
> > => #<File:numbers.txt>
> >
> > f.each {|line| puts line}
> > => #<File:numbers.txt>
> >
> > Why doesn't the second f.each work?
>
> because as each iterates through the file it "consumes" the file
> contents (well, it remembers how far it has got.)  You can usually
> rewind a file to the beginning, so:
>
> irb(main):001:0> f = File.new('numbers.txt')
> => #<File:numbers.txt>
> irb(main):002:0> f.each {|line| puts line}
> 123
> 456
> 789
> => #<File:numbers.txt>
> irb(main):003:0> f.pos
> => 12
> irb(main):004:0>  f.each {|line| puts line}
> => #<File:numbers.txt>
> irb(main):005:0> f.pos
> => 12
> irb(main):006:0> f.rewind
> => 0
> irb(main):007:0>  f.each {|line| puts line}
> 123
> 456
> 789
> => #<File:numbers.txt>
>
> Note that some types of file can't be rewound.
>
> Take a look at what the pos method does, and see if this makes sense.
>
> Hope this helps,
>
> Mike
>
> --
>
> Mike Stok <mike@stok.ca>
> http://www.stok.ca/~mike/
>
> The "`Stok' disclaimers" apply.
>
>
>
>
>
>

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