From: Chris Hulan <chris.hulan@...>
Date: 2009-03-07T13:38:26+09:00
Subject: Re: text processing

On Mar 6, 9:38 pm, Ruby Kk <kumar...@gmail.com> wrote:
> Hi there,
> I am new to ruby and trying to create a flat file with fixed column
> length. i have a header,footer and records that i want in the file.
>
> any ideas?
>
> Cheers!
>
>
>
> Gary Wright wrote:
> > On Mar 30, 2007, at 3:31 PM, Stephen Smith wrote:
> >> {9})/.match(line).captures.join(',')
> >> << "\n"
> >> newLogg << record
> >> record = ""
> >> end
>
> > How about making it so you don't have to type that pattern next time:
>
> > def columns(*widths)
> >    Regexp.new(widths.map {|count| "(.{#{count}})" }.join)
> > end
> > pattern = columns(6,15,3,30,4,15,1,12,9)
>
> > You also can get rid of the intermediate strings and the potentially
> > huge
> > internal array (from slurping up your oldLog into an array):
>
> > oldLog.each { |line|
> >    newLog.print pattern.match(line).captures.join(',')
> > }
>
> --
> Posted viahttp://www.ruby-forum.com/.

sprintf allows you specify formatting that can be used to print fixed
width.
An example from the docs (ruby-doc.org) is:
sprintf("%08b '%4s'", 123, 123)            #=> "01111011 ' 123'"
Note how the %4s puts 3 characters in a space 4 characters wide.

cheers