1.6 KiB
1.6 KiB
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| Ruby Hashes |
Ruby Hashes
A hash is a collection of keys and values. It is similar to what is commonly called a dictionary in other languages. In Ruby, a hash is similar to an array, but rather than simply storing a value it stores a key, value pair.
array = ["value"]
hash = { "key" => "value" }
There are a couple of different ways to create a new hash:
hash1 = {a: 100, b: "200"}
hash2 = Hash.new
hash3 = Hash.new(0) # with default value set to 0
A programmer can then access a hash value using its key, rather than the index.
array[0] # => "value"
hash["key"] # => "value"
In this way, a hash acts more like a dictionary where you can look up a value by its key.
dictionary = { "Aardvark" => "a large, nocturnal, burrowing mammal",
"Zyzzyva" => "a genus of tropical weevils" }
dictionary["Aardvark"] # => "a large, nocturnal, burrowing mammal"
dictionary["Zyzzyva"] # => "a genus of tropical weevils"
You can also create a hash using symbols as keys.
hash = { :symbol => "value" }
hash[:symbol] # => "value"
In addition, if all of your keys are symbols, you can write your hash in this alternate format, but you would access it in the same manner:
hash = { symbol: "value" }
hash[:symbol] # => "value"