block_benchmark.rb

def benchmark
  # Your benchmarking code goes here.
  start_time=Time.now

  yield    # yield (long_string.reverse) ==> execute command in {}

	end_time=Time.now

	end_time-start_time    #return back to running_time below

end

# Be careful, pasting this into IRB will take a long time to print.
# It's a loooong string. :)
long_string = "apple"*100000000

running_time = benchmark { long_string.reverse }

puts "string.reverse took #{running_time} seconds to run"