string.gmatch vs string.sub

subvsmatch.lua

-- Calls f(...) n-times
local function time(nm,times, f,...)
  local st = os.clock()
  for i = 1, times do
    f(...)
  end
  local et = os.clock()
  print(('(%s): Times (%d): %.2f ms')
    :format(nm, times, (et-st)*1000))
end

-- string.sub test
local function test_sub(str)
  local char
  for i = 1, #str do
    char = str:sub(i,i)
  end
end

-- string.gmatch test
local function test_gmatch(str)
  for i in str:gmatch('.') do
  end
end

-- Makes a string
local function make_string(len)
  local str = ''
  for i = 1,len do
    local s = string.char(math.random(255))
    str = str .. s
  end
  return str
end

math.randomseed(os.time())
local str = make_string(1e4)
time('gmatch', 1000, test_gmatch, str)
time(   'sub', 1000, test_sub, str)