CODEWITHSUNDEEP
ruby
Samuel Okoth
Samuel Okoth

Reputation: 139

What does the 'undefined method `+' for nil:NilClass (NoMethodError)' error in my ruby code mean?

newbie here. So I was coding along on youtube and found the following error 'undefined method `+' for nil:NilClass (NoMethodError)'. I know the code works because it was able to run in the video but when I tried to run it, I received the error.

The following is my code:

def caesar_cipher(string, num)
  alphabet = ("a".."z").to_a
  caesar = ""
  string.each_char do |letter|
    if letter == " "
      caesar += " "
    else
      old_idx = alphabet.find_index(letter)
      new_idx = (old_idx + num) % alphabet.count
      caesar += alphabet[new_idx]
    end
  end
  caesar
end

puts caesar_cipher("What a string!",5)

What could be causing the error? Any help will be appreciated :)

Upvotes: 0

Views: 609

Answers (1)

spike 王建
spike 王建

Reputation: 1714

The function only works 'a'..'z' as @Jeremty mentioned, so W and ! will be nil.If you want to keep every none alphabet char, the following code maybe help.

def caesar_cipher(string, num)
  alphabet = [*'a'..'z', *'A'..'Z']
  caesar = ""
  string.each_char do |letter|
    old_idx = alphabet.find_index(letter)
    if old_idx.nil?
      caesar += letter
    else
      new_idx = (old_idx + num) % alphabet.count
      caesar += alphabet[new_idx]
    end
  end

  caesar
end

puts caesar_cipher("What a string!",5)

Upvotes: 2

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