Ruby 获取对象键作为数组

我是 Ruby 的新手，如果我有这样一个对象的话

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

如何返回仅包含键的数组？

["apple", "carrot"]

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小开

最佳答案

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

it's that simple

小开

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

小开

Like taro said, keys returns the array of keys of your Hash:

You'll find all the different methods available for each class.

If you don't know what you're dealing with:

 puts my_unknown_variable.class.to_s

This will output the class name.

小开

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 that if you want to manipulate the array while retrieving it..