From: Tim Hunter <TimHunter@...>
Date: 2008-11-16T10:00:34+09:00
Subject: Re: IO#lineno= doesn't work the way I expected

Jens Wille wrote:
> hi chad!
> 
> Chad Perrin [2008-11-16 01:32]:
>> On Sun, Nov 16, 2008 at 05:42:18AM +0900, Tim Hunter wrote:
>>> Chad Perrin wrote:
>>>> 2. Is there a way to do what I actually need -- specifically,
>>>> to iterate over an entire file *except* the first line, only
>>>> reading one line at a time into RAM -- without writing a C
>>>> extension for Ruby?
>>> Why not iterate over the entire file and just ignore the first
>>> line? IO#readline or IO#gets will get you a line at a time.
>> How do you propose I "ignore" the first line?  That's what I was
>> trying to do -- by starting the iteration over lines in the file
>> with the second line.  Are you saying I should just have an
>> orphan gets line in the code, then have a block in which I use
>> gets each line until I run out of file? I guess that would
>> probably work, but seems kinda . . . ugly.
> not sure what tim was suggesting, but this will work:
> 
>   in_fh = File.open(infile, 'r')
>   out_fh = File.open(outfile, 'w')
> 
>   # ignore first line
>   in_fh.gets
> 
>   in_fh.each_line do |l|
>     out_fh << l
>   end
> 
> ok, it's not pretty, but not *that* ugly either, is it? ;-)
> 
> cheers
> jens
> 
> 

That's almost precisely what I was suggesting. For real code I'd want to 
handle the case of the file not having any lines, if that can occur. It 
doesn't look "ugly" to me at all.

-- 
RMagick: http://rmagick.rubyforge.org/