Benchmark of different way to make a name string from first_name and last_name

benchmark_names.rb

# Note: I realize this is trivial, but this is a pattern I use a lot (name from first/last) so I was
# curious as to which method was quicker, and if perhaps I've been doing it wrong...? Run on 1.9.3

require 'benchmark'

first_name = "john"
last_name = "smith"
i = 1000000

# Reopen string to add the blank? method
class String
  def blank?
     self !~ /[^[:space:]]/
  end
end

Benchmark.bm(7) do |x|
  x.report("string: ") { i.times { "#{first_name} #{last_name}" }}
  x.report("array join: ") { i.times { [first_name, last_name].join(" ")  }}
  x.report("array join with rejection: ") { i.times { [' ', last_name].reject(&:blank?).join(" ") }}
  x.report("concat: ") { i.times { first_name + " " + last_name }}
  x.report("sprintf: ") { i.times { sprintf("%s %s", first_name, last_name) }}
end

results.txt

             user     system      total        real
string:   0.680000   0.000000   0.680000 (  0.677926)
array join:   1.190000   0.030000   1.220000 (  1.245561)
array join with rejection:   5.510000   0.020000   5.530000 (  5.531430)
concat:   0.680000   0.000000   0.680000 (  0.683626)
sprintf:   1.340000   0.010000   1.350000 (  1.346253)