Ruby Quicktips

Use negative Array indices

Ruby arrays have some nifty behavior when passed negative array indices. Let’s say you have an array

array = [:a, :b, :c, :d, :e]

You can access the last element in the array by calling

array[-1] # => :e

The second-to-last element has index -2, and so on. Negative indices also work for slicing operations. For example, if you wanted to leave out the last two elements in the array, you would call

array[0..-3] # => [:a, :b, :c]

and if you wanted to remove just the first element of the array,

array[1..-1] # => [:b, :c, :d, :e]

This tip was submitted by Rockwell Schrock.