String concatenation benchmark in ruby

What to use for concatenate strings in ruby , "+=" or "<<" or concat() ? Here is a benchmark that can guide if concatenations is in a loop.

def benchmark_string_concatenation n

Benchmark.bm(10) do |x|

x.report("With '+=' :") {string = ""; n.times {|n| string += "e"} }

x.report("With '<<' :") {string = ""; n.times { |n|string << "e"} }

x.report("With #concat :") {string = ""; n.times { |n|string.concat("e")} }

end 

end

Results with n = 5000:

              user      system    total     real
With '+='   : 0.010000 0.010000 0.020000 ( 0.022831)
With '<<'   : 0.000000 0.000000 0.000000 ( 0.001734) 
With concat : 0.000000 0.000000 0.000000 (0.001689)

Results with n = 50000:

                user    system    total   real
With '+='   : 0.710000 0.000000 0.710000 ( 0.737932)
With '<<'   : 0.020000 0.000000 0.020000 ( 0.019771)
With concat : 0.020000 0.000000 0.020000 ( 0.019853)