From: Rob Biedenharn <Rob@...>
Date: 2007-02-09T10:10:13+09:00
Subject: Re: Iterators and blocks question

On Feb 8, 2007, at 7:05 PM, oinkoink wrote:
> On Feb 8, 3:25 pm, "oinkoink" <oinkoink+u...@rexx.com> wrote:
>> require 'mathn'
>> width = (Math.log((rl = IO.readlines("test.txt")).length)/
>> Math.log(10)).floor + 1
>> rl.each_with_index{ |line, k| print "%#{width}d. " % k  + line}
>
> Following up to myself, the idea is to keep from indenting the lines
> differently
> every time the line number passes a power of 10.
> Regards, Bret

   width = (rl = IO.readlines("test.txt")).length.to_s.length
   format = "%2$#{width}d: %1$s" # see Kernel#sprintf
   rl.each_with_index { |*ary| ary[1] += 1; print format % ary }

The ary[1]+=1 part is to make the numbers 1-based.  If you're OK with  
the zero, leave it out.  Of course, if you want to start with 1, it  
makes more sense to do:

   number = 0
   rl.each { |line| number += 1; print format % [ line, number ] }

or

   rl.each_with_index { |line,number| print format % [ line, number 
+1 ] }

But then you could go back to the simpler format string and swap the  
order of the args yourself.

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com