Learn Ruby the Hard Way: A Simple and Idiomatic Introduction to the Imaginative World of Computational Thinking with Code, Third Edition

Exercise 39. Hashes, Oh Lovely Hashes

Now I have to hurt you with another container you can use, because once you learn this container a massive world of ultra-cool will be yours. It is the most useful container ever: the dictionary.

Ruby calls them “hashes”, which is short for “hashmaps.” Other languages call them “dictionaries.” I tend to use both names, but it doesn’t matter. What does matter is what hashs do when compared to arrays. You see, an array lets you do this:

Exercise 39 Ruby Session

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?> things = ['a', 'b', 'c', 'd'] => ["a", "b", "c", "d"] >> puts things[1] b => nil >> things[1] = 'z' => "z" >> puts things[1] z => nil >> things => ["a", "z", "c", "d"]

You can use numbers to “index” into a array, meaning ...