(1..5) # => 1, 2, 3, 4, 5
(1...5) # => 1, 2, 3, 4You can use letters or numbers in a range.
The items in the range must increment. If you want the items to descend rather than ascend, make the range as usual and then call reverse on it.
Store pieces of data in a list that can be retrievesd by number (or rather, by index).
A quick way of filling an array with strings:
%w(hello there) # => ["hello", "there"]array.each # => Loops over each item in an array
array.map # => Does something to each item in an array, and creates a new array of the same size from the results
array.map! # => Like map, but overwrites the original array with the result of the process
array.select # => Evaluates a condition and returns matching items from the array
array.reject # => Does the opposite of select!These store key-value pairs. Keys must be unique. In other languages, hashes are called dictionaries.
Values can be retrieved from a hash by specifying a key.
hash = Hash.new
hash = {:name => "Henry", :city => "London", :age => 150}
hash[:city] # => returns "London"As of Ruby 1.9, hashes have a fixed order.