Re: string.random
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- Subject: Re: string.random
- From: Adrian Sietsma <adrian_groups@...>
- Date: 2004年7月17日 18:21:00 -0700
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