Re: common prefix?
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- Subject: Re: common prefix?
- From: Duncan Cross <duncan.cross@...>
- Date: 2009年7月16日 20:21:56 +0100
On Thu, Jul 16, 2009 at 8:03 PM, Petite Abeille<petite.abeille@gmail.com> wrote:
> Hello,
>
> Does anyone has a little function to compute the common prefix of a list of
> strings?
>
> E.g.:
>
> local aList = { 'foobarbaz', 'foobar', 'foo' }
>
> print( CommonPrefix( aList ) )
>
>> foo
>
> TIA.
>
> Cheers,
>
> PA.
Hi PA,
This is how I would do it:
--
local function commonprefix_aux(a,b,max)
local count = 0
for i = 1,max do
if (string.sub(a,i,i) ~= string.sub(b,i,i)) then
return count
end
count = count + 1
end
return count
end
function commonprefix(list)
local first
local prefixsize
for i,v in ipairs(list) do
if (i == 1) then
first = v
prefixsize = #first
else
prefixsize = math.min(prefixsize, commonprefix_aux(first,v,prefixsize))
if (prefixsize == 0) then
break
end
end
end
return string.sub(first or '',1,prefixsize or 0)
end
--
-Duncan