scountbench.rb

require 'benchmark'

TIMES = 4_000
s = "you like to play with your yo-yo" * 100
Count = 400

def check!
  abort "count not #{Count} but #{@count}" unless @count == Count
end

Benchmark.bmbm do |x|
 x.report("scan") do
   TIMES.times do
       @count = s.scan("yo").size
   end
   check!
 end

 x.report("scan ++") do
   TIMES.times do
       @count = 0
       s.scan("yo") { @count += 1 }
   end
   check!
 end

 x.report("scan re") do
   TIMES.times do
     @count = s.scan(/yo/).size
   end
   check!
 end

 x.report("scan re ++") do
   TIMES.times do
       @count = 0
       s.scan(/yo/) { @count += 1 }
   end
   check!
 end

 x.report "gsub" do
   TIMES.times do
     @count = s.size - s.gsub("yo","").size
     @count /= "yo".size
   end
   check!
 end
 x.report("while") do
   TIMES.times do
     len   = "yo".length
     index = -len
     @count = 0
     while index = s.index("yo", index + len)
       @count += 1
     end
   end
   check!
 end
end