Re: finding keys in a table

["Alex Davies" <alex.mania@...>]

Exactly as you list:

From: "Jelle Huisman" <jelle@jhnet.nl>
> (1) lookup if the current character already exists as a key in the table.
> (2a) If it does exist I increment the value for key currentchar with 1
> (2b) else I add a new entry: currentchar=1
> (3) Later I sort the table and print my freq.list.

if tab[char] ~= nil then  -- (1) is the char in the table?
 tab[char] = tab[char] + 1  -- (2a) then increment
else
 tab[char] = 1  -- (2b) else add new entry
end

(It could also be written like this, for a bit more speed: )
local count = tab[char]
tab[char] = (count or 0) + 1  -- initializes count if necessary (an 
explanation can be found at: http://www.lua.org/pil/3.3.html)

Because you can't sort key/value pairs, sorting is a little bit more 
complicated:

local reverse = {}
for k,v in pairs(tab) do
 reverse[#reverse+1] = { k, v }
end
table.sort(reverse, function(a, b) a[2] < b[2] end)