Question

I’m sorry if I may have missed a documentation topic on this.

What does the double dot mean on this piece of code:

require 'benchmark'
iterations = 1000000

b = Benchmark.measure do
  for i in 1..iterations do
    x = i
  end
end

c = Benchmark.measure do
  iterations.times do |i|
    x = 1
  end
end

puts b
puts c

I am new to Ruby so please be easy on me 😛

Answer 1

.. indicates a Range object going from the number on the left to the number on the right. This can be best shown by converting the object to an Array object, like this:

>> (1..10).to_a
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] 

See? This object provides a range of digits from 1 through to 10.

It also works for sequential letters:

>> ("a".."j").to_a
=> ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j"]

The Range class includes the Enumerable module which gives us the each method, allowing us to iterate over each element inside the range.

Additonal trivia:

... is also used in Ruby, except it gets everything up to but not including the value on the right.

>> (1...10).to_a
=> [1, 2, 3, 4, 5, 6, 7, 8, 9]