Ruby Array #bsearch syntax error from Programming Ruby?

Question

Copying this code from book Programming Ruby and running it in rubyfiddle.com . Getting syntax error instead of # => 21 ? Any help is appreciated!

arr = [ 1, 1, 2, 3, 5, 8, 13, 21, 34 ]
res = arr.bsearch do |val|
  case
    when val < 19 then +1
   when val > 23 then -1
   else 0
  end    
end
   
res # => 21

Could you just copy the error or error line and post it in your question please. — Pavan, May 06 '14 at 15:41
@Pavan (eval):48: undefined method `bsearch' for [1, 1, 2, 3, 5, 8, 13, 21, 34]:Array (NoMethodError) => I get this error in labs.codecademy.com — user3222947, May 06 '14 at 15:42
http://stackoverflow.com/questions/8672472/is-there-a-built-in-binary-search-in-ruby — Dave Newton, May 06 '14 at 15:51
The code is weirdly written and even more weirdly formatted, but I don't see any syntax error in the code. Please provide the *exact* code that is giving you the syntax error, tell us *which line* the error occurs on and provide the *exact* error message. — Jörg W Mittag, May 06 '14 at 21:12

score 2 · Accepted Answer · answered May 06 '14 at 16:01

Having tested your code myself, there is nothing wrong with what you have written. In all likelihood you (or in this case, codecademy) are using an older version of Ruby. The bsearch method was defined on Array and Range in Ruby 2.0. Prior to Ruby 2.0, there were several gems that could be used to perform a binary search on an array.

To test which version of Ruby you are using, type the following into irb or your codecademy console:

> RUBY_VERSION
=> "2.1.1"

If the number returned is less than "2.0", bsearch will not be natively defined for either Array or Range

@JörgWMittag yes it does, if you read the OP's comments, the error was `undefined method 'bsearch' for [1, 1, 2, 3, 5, 8, 13, 21, 34]:Array(NoMethodError)` — wvandaal, May 06 '14 at 21:11

Micka · Answer 2 · 2014-05-07T08:29:24.407

0

As you specified in one of your comment the exact error is:

(eval):48: undefined method `bsearch' for [1, 1, 2, 3, 5, 8, 13, 21, 34]:Array (NoMethodError)

This error means the method bsearch doesn't exist for Array.

In labs.codecademy.com

 > RUBY_VERSION
=> "1.8.7"

There is no bsearch in Ruby 1.8.7.
bsearch has been implemented in Ruby 2.0.

edited May 07 '14 at 08:29

answered May 06 '14 at 15:59

Micka

1,648
1
19
34

The exact error, as specified in one of the comment by @user3222947 is `(eval):48: undefined method 'bsearch' for [1, 1, 2, 3, 5, 8, 13, 21, 34]:Array (NoMethodError)` – Micka May 07 '14 at 08:23
@JörgWMittag, I added the specified error in my answer. – Micka May 07 '14 at 08:30
That's not a syntax error (`SyntaxError`), that's a semantic error (`NoMethodError`). The OP mentioned three times that he is getting a syntax error as well, *that's* what I am puzzled by. The `NoMethodError` is obvious. – Jörg W Mittag May 07 '14 at 08:33
@JörgWMittag, You have it. The `syntax error` in the question only means `error`. Then the error should have been specified as well in the question but is only written in the comment section. There are many misleading mistakes here. – Micka May 07 '14 at 08:38

Ruby Array #bsearch syntax error from Programming Ruby?

2 Answers2