From: Joseph Paish <jepaish@...>
Date: 2005-07-13T22:07:43+09:00
Subject: correct use of join?

when i run a (large) script i am writing, this is the output i get on the 
screen (there are actually several hundred lines of output).  note the "nil" 
on the first line.

nil
["10/12/2001", "bought", "10000", "abc", "0.100", 0.2345, "17.43"]
["01/02/2005", "sold", "100", "widget2", "0.143", 0.4567, "22.45"]

assuming that each line of the output is called single_record, when i type 
single_record.class, i find out that it is an Array.  so far, so good.

when i include the line 

puts single_record.join(" ") 

in the script in order to print single_record out as a space-separated string, 
i get the following message : 

my_command_prompt$ ruby ~/ruby_dir/program_name.rb
nil
/my_command_prompt/ruby_dir/program_name.rb:377: undefined method `join' for 
nil:NilClass (NoMethodError)
        from /my_command_prompt/ruby_dir/program_name.rb:239:in `each'
        from /my_command_prompt/ruby_dir/program_name.rb:239

when i use irb to do the example on the web page 
http://pine.fm/LearnToProgram/?Chapter=07, everything works perfectly.  

if single_record is in fact an array (and single_record.class tells me it is), 
what am i doing wrong?  I have a feeling it has to do with the appearance of 
the word "nil" in the first line of output.

thanks

joe