string.rb

require 'benchmark'

n = 1000000
Benchmark.bm(15) do |x|
  x.report("assign single") { n.times do; c = 'a string'; end}
  x.report("assign double") { n.times do; c = "a string"; end}
  x.report("concat single") { n.times do; 'a string ' + 'b string'; end}
  x.report("concat double") { n.times do; "a string " + "b string"; end}
end


# $ ruby -v 
# ruby 2.0.0p353 (2013-11-22 revision 43784) [x86_64-darwin13.0.0]
# $ ruby string.rb
#                      user     system      total        real
# assign single     0.140000   0.000000   0.140000 (  0.136359)
# assign double     0.130000   0.010000   0.140000 (  0.134131)
# concat single     0.330000   0.000000   0.330000 (  0.331155)
# concat double     0.340000   0.000000   0.340000 (  0.339431)