Hash

  • Hashrocket vs JSON-Style

  • Hash key can be a string or a symbol.

  • Using symbols as hash keys is preferred whenever possible.

  • Every instance of a symbol points to the same object, whereas each instance of a string refers to a unique object.

  • Using symbols as keys results in slightly better performance and less memory usage.

a = {} (or a = Hash.new)
a['one'] = 1 # a = {"one"=>1}
a['two'] = 2 # a = {"one"=>1, "two"=>2}

Symbol Key:#

  • This is more popular.
temp = { first_message: "this is a message",
"third_message": "this is third message",
:fourth_message => "this is a fourth message"}
  • Access symbol keys:
2.6.3 :024 > temp[:first_message]
=> "this is a message"
2.6.3 :022 > temp[:third_message]
=> "this is third message"
2.6.3 :028 > temp[:fourth_message]
=> "this is a fourth message"

String Key:#

temp = { "second_message" => "this is a second message" }
  • Access String keys:
2.6.3 :023 > temp["second_message"]
=> "this is a second message"

Resources:#

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