Question

I am writing this code for a CS assignment in Ruby. I am just beginning in Ruby so I don’t know much about it but I keep getting a no method error from this code like this:

V:\CS 300 RubyAssignment\lib\rubyAssignment.rb:13:in `categorize': undefined method `line' for #<File:ruby1.txt (closed)> (NoMethodError)
    from V:\CS 300 RubyAssignment\lib\rubyAssignment.rb:11:in `open'
    from V:\CS 300 RubyAssignment\lib\rubyAssignment.rb:11:in `categorize'
    from V:\CS 300 RubyAssignment\lib\rubyAssignment.rb:30

The code is below but I get a feeling my text files are in the wrong place. I use a NetBeans Ruby plugin and I don’t know if my text files should be in the projects source file folder, test file folder or libraries folder in netbeans? It might be as simple as that any ideas?

# This program reads a file line by line,
# separating lines by writing into certain text files.
# PPQ - Pangrams, Palindromes, and Quotes

class PPQ
  def categorize
    file_pangram = File.new('pangram.txt', 'w')
    file_palindrome = File.new('palindrome.txt', 'w')
    file_quotes = File.new('quotes.txt','w')

    File.open('ruby1.txt','r') do |file|
      while line = file.gets
        if(file.line.reverse == file.line)
          file_palindrome.write line
          if(file.line.contains('a'&&'b'&&'c'&&'d'&&'e'&&'f'&&'g'&&'h'&&'i'&&'j'&&'k'&&'l'&&'m'&&'n'&&'o'&&'p'&&'q'&&'r'&&'s'&&'t'&&'u'&&'v'&&'w'&&'x'&&'y'&&'z'))
            file_pangram.write "file.line"
          else
            file_quotes.write "file.line"
          end
        end
      end
      file.close
      file_pangram.close
      file_palindrome.close
      file_quotes.close
    end
  end
end
my_ruby_assignment = PPQ.new
my_ruby_assignment.categorize

Answer 1

The clue’s in the error message!

undefined method line

In your while loop you’re reading a line from file via gets, then storing it in line. This code:

if(file.line.reverse == file.line)

is therefore incorrect — you don’t need the file. prefix! Ruby thinks you’re trying to call the line method of the file object, which it doesn’t have. That’s why it’s giving you the error it did…