From: ahoward <ahoward@...>
Date: 2003-06-22T07:44:35+09:00
Subject: Re: reading text line

On Sat, 21 Jun 2003, Dan wrote:

> i want to read a line of string from a file every other line
>
> line one
> line two
> line three
> line four
>
> want it to print
>
> line one
> line three
>
> -------------------f = File.new("testfile")
> f.each {|line| puts "#{f.lineno}: #{line}" }
>
>
>
> should i have
> #(f.lineno)/2 == true
> ...do something
>
> else...do somethin else?

use %

/usr/home/howardat > cat odds.rb
#!/usr/bin/env ruby

cat = IO.popen 'cat', 'w+'
cat.write DATA.read
cat.close_write

# the pertinent bit
print if $. % 2 == 0 while cat.gets


__END__
zeroth
first
second
third
fourth
fifth
sixth
seventh
eigth
ninth

/usr/home/howardat > ruby odds.rb
first
third
fifth
seventh
ninth


-a
--
  ====================================
  | Ara Howard
  | NOAA Forecast Systems Laboratory
  | Information and Technology Services
  | Data Systems Group
  | R/FST 325 Broadway
  | Boulder, CO 80305-3328
  | Email: ara.t.howard@noaa.gov
  | Phone:  303-497-7238
  | Fax:    303-497-7259
  | ~ > ruby -e 'p(%.\x2d\x29..intern)'
  ====================================