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Brief Info About Hash

What is the hash in ruby ?

Hash, hash, hash ?

  • Hashes are one of the biggest property which separated another language in ruby.
  • Hash was known associative array in another programming language.
  • In hash, elements keep ‘key => value’ format in ruby . Like
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hash_example = { 'name' => 'John', 'surname' => 'doe' }
  • Values of keys can be any type, but when you use ‘eql?’ method, it can be only a key according to each other.
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    a = { 3 => 'three', 3.0 => 'threedotzero' }
    a[3]        #three
    a[3.0]      #threedotzero
    3 == 3.0        #true
    3.eql? 3.0      #false
  • Hashes usually write with symbols, like :
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 hash_with_symbol{ name: 'John', surname: 'Doe'}
  • Hashes are similar to Array class, but Array uses integer as its index, hash allow to us any object type.
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hash_differences_array{ 'age' => 15, 'year' => 2014 }
array_differences_hash = [1, 2, 3]

In my opinion, You have an information about hashes. Do you agree with me?!

  • Continue to learn!, I have an information about hash, but if I want to access only keys or values , How does it access or separate these in hash ?

For this question, solution: if you want to access to keys use

        keys

method, if you want to access to values use

        values

methods. Like:

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access_values_keys{ name: 'john', surname: 'Doe'}
access_values_keys.keys         # [:name, :surname]
access_values_keys.values       #['John', 'Doe']
  • Generally, hashes are using in parameters of name,
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def parameters_name(name, age)
    '#{name} : #{age}'
end
puts name 'John' , 18       # Ali : 18
  • Hashes uses to ENUMERABLE module like arrays.
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  {}.class.ancestors          #show the hash ancestors.
                                        #[Hash, Enumerable, Object, PP::ObjectMixin, Kernel, BasicObject]
  • If you want to change from array to hash, you should use
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.to_h

Lastly If you want to learn more, you can visit ruby-doc .

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