Test Enumerable#sort_by! vs. Enumerable#sort_by in Ruby. Results ran under MRI.

output.txt

$ ruby -v
ruby 1.9.3p374 (2013-01-15 revision 38858) [x86_64-darwin12.2.1]
$ ruby sort_test.rb

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Bang results:  0.8399645
Normal results:	0.8487451699999999

sort_test.rb

TIMES = 100

arr = (1..1_000_000).to_a

sort_by_bang_results = []
sort_by_results = []

def time(&blk)
  start_at = Time.now
  yield
  Time.now - start_at
end

TIMES.times do |i|
  puts i
  randoms = arr.shuffle

  sort_by_randoms = randoms.dup
  sort_by_bang_randoms = randoms.dup

  sort_by_bang_results << (time { sort_by_bang_randoms.sort_by! { |i| i } })
  sort_by_results << (time { sort_by_randoms.sort_by { |i| i } })
end

puts "Bang results:\t#{sort_by_bang_results.reduce(&:+) / TIMES.to_f}"
puts "Normal results:\t#{sort_by_results.reduce(&:+) / TIMES.to_f}"