Re: string.random

[Adrian Sietsma <adrian_groups@...>]

Markus Huber wrote

> > I would like to use a function to generate an string with "random"
> > characters. ...

This should be faster than the hack you supplied, as it
1/ only creates patterns once, and
2/ uses table.concat for the string concatenations.
3/ uses table lookups rather than string.char.
(but i haven't tested it - this is just an outline)

Adrian

<CODE>
do -- block for upvalues
   local AllChars = {}
   for Loop=0,255 do
      AllChars[Loop+1]=string.char(Loop)
   end
   local AllString = table.concat(AllChars)

   local Built = {'.',AllChars}

   local function AddLookup(Pattern)
      local S=string.gsub(AllString,'[^'..Pattern..']','')
      local Lookup = {}
      for Loop=1,string.len(S) do
         Lookup[Loop] = string.sub(S,Loop,Loop+1)
      end
      Built[Pattern] = Lookup
      return Lookup
   end

   function RandomString(Length,Pattern)
 -- Length (number)
 -- Pattern (string, optional);
 -- e.g. %l%d for lower case letters and digits

      local Pattern = Pattern or '.'
      local Lookup = Built[Pattern] or AddLookup(Pattern)
      local Range = table.getn(Lookup)
      local Result = {}

      for Loop=1,Length do
         Result[Loop] = Lookup[math.random(1,Range)]
      end

      return table.concat(Result)
   end  -- function

end -- do

</CODE>

Adrian