From: Justin Collins <justincollins@...>
Date: 2008-02-28T06:46:08+09:00
Subject: Re: checking for blank line

Jeff Miller wrote:
> Hello,
>  I know this is an elementary problem, but I have been fooling around
> with RoR for a little while and am now in need of doing some ruby
> scripting. I am reading a text file line by line and I want to check if
> the line is empty. For example:
>
> file = File.new("test.txt", "r")
> while (line = file.gets)
>   @array = line.split(':')
>     if @array[0] == 'cn'
>       puts "#{@array[1]}"
>     end
>     if @array[0] == 'title'
>       puts "   Title: #{@array[1]}"
>     end
>     if @array[0] == 'company'
>       puts "   Company: #{@array[1]}"
>     end
>     if @array[0] == nil              #~ THIS IS THE LINE I'M TALKING
> ABOUT
>       puts "-----"
>     end
> end
> file.close
>
> The input file just looks like this:
>
> cn: John Smith
> title: executive
> company: ReallyCoolSoftware, inc.
>
> cn: John Doe
> title: janitor
> company: NotSoCoolSoftware, inc.
>
> etc...
>
> How can I pick up those blank lines in my IF statement? I tried nil and
> '', but neither seem to work.
>
> Any help is appreciated!
> Thank you!!
>  - Jeff
>   


Remember, "blank" lines might not be truly empty:
irb(main):001:0> a = gets

=> "\n"
irb(main):002:0> a.split(":")
=> ["\n"]

Also, using split on an empty string is not going to give you nil, but 
an empty array:

irb(main):003:0> "".split(":")
=> []

If you don't want the line endings in your strings, try using

while (line = file.gets.chomp)

or

while (line = file.gets.strip)


instead.

-Justin