Ruby gets object keys as an array

Question

I am new to Ruby if I have such an object

{"apple" => "fruit", "carrot" => "vegetable"} 

How can I return an array of keys only?

 ["apple", "carrot"] 

Answer 1

 hash = {"apple" => "fruit", "carrot" => "vegetable"} array = hash.keys #=> ["apple", "carrot"] 

it's simple

Answer 2

An alternative way if you need something more (besides using the keys method):

 hash = {"apple" => "fruit", "carrot" => "vegetable"} array = hash.collect {|key,value| key } 

obviously, you would only do this if you wanted to manipulate the array while retrieving it.

Answer 3

Like taro, keys returns an array of keys for your hash:

http://ruby-doc.org/core-1.9.3/Hash.html#method-i-keys

You will find all the different methods available for each class.

If you do not know what you are dealing with:

  puts my_unknown_variable.class.to_s 

This will display the class name.

Answer 4

Use the keys method: {"apple" => "fruit", "carrot" => "vegetable"}.keys == ["apple", "carrot"]