CODEWITHSUNDEEP
ruby
Iván Cortés
Iván Cortés

Reputation: 652

What's the difference `{'x'=> 3}` and `{x: 3}`?

I have this:

a = {'x' => 3}
b = {'x': 3}
c = {x: 3}
d = {:x => 3}
e = {:'x' => 3}

So, I have that b = c = d = e = {:x => 3}, meanwhile a = {"x" => 3} but a.class == b.class.

I don't understand what the difference is between a and the rest of variables.

Upvotes: 0

Views: 91

Answers (3)

cozyconemotel
cozyconemotel

Reputation: 1161

In b,c,d, and e, the key is a Symbol.

In a, the key is a String.

a = { 'x' => 3 }  #=> { "x" => 3 } 
b = { 'x': 3 }    #=> { :x => 3 }
c = { x: 3 }      #=> { :x => 3 }
d = { :x => 3 }   #=> { :x => 3 }
e = { :'x' => 3 } #=> { :x => 3 }

Upvotes: 2

Aleksei Matiushkin
Aleksei Matiushkin

Reputation: 121000

There is a significant difference between String and Symbol classes in ruby:

By convention, all but the very first hash notations cast keys to the Symbol instance, while the first one uses the key (String instance in this particular case) as is. (To be more precise: b and c cast key to the Symbol instance, d and e do not cast anything, but keys given in these cases are Symbol instances already.)

Since ('x' == :x) == false, a hash differs from the latters.

Upvotes: 0

Petr Gazarov
Petr Gazarov

Reputation: 3821

Your variable a hash has "x" key as a string, while other variables have that key as symbol.

Calling class on an object in Ruby returns its class, in your example it is Hash. In other words, the constructor of all hash instances, such as {x: 3} is Hash object.

Upvotes: 2

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