rubyuntil-loop

Ruby Until-Loop: undefined method `[]' for nil:NilClass (NoMethodError)

Note: I am a novice at Ruby.

Question: How can i get print3 to print out the array, using an until loop? This may be more simple than I realise, but i've spent a good few hours trying to solve the below. All I can find are 'simple' until loop examples.

I have a method (print3), that I specifically need to use an until-loop on. print3 pulls an array from the input_students method. both methods are below.

I get the following in irb - directory.rb:30:in ``print3``: undefined method[]for nil:NilClass (NoMethodError). Line 30 refers to 

puts "#{i+1} #{students[i][:name]} (#{students[i][:cohort]} 
cohort)"

My code:

def input_students
  puts "Please enter the names of the students"
  puts "To finish, just hit return twice"

  students = []

  name = gets.chomp.downcase

  while !name.empty? do

   students << {name: name, cohort: :november}
   puts "Now we have #{students.count} students"

   name = gets.chomp.downcase
  end

 students

end

def print3(students)
 i = 0
 until i > students.length

  puts "#{i+1} #{students[i][:name]} (#{students[i][:cohort]} 
  cohort)"
  i += 1
 end
end

Thanks for any help you can provide.

Solution

  • As @Tom Lord mentioned, you want your loop to stop when i == students.length

    The first element of the array is index 0, the second is index 1. That means your array is length 2 but there is no element at index 2, since you're incrementing by 1 you want to stop your loop there.