My program filters some uneven numbers but also some even numbers

Question

So I need to write a program which gets a table as an input and gives the same table as an output without the values with even keys. So basically I need to filter out the even keys and their values and leave the uneven keys with their values.

local function selecteer_oneven(tabel)
    for q, n in ipairs(tabel) do
    if (q % 2) == 0 then
      table.remove(tabel, q)
    end
  end
  return tabel
end

local function printtabel(tabel)
    for k,v in pairs(tabel) do
        print(k,v)
    end
end

io.write("Geef een lua-tabel: ")
local tabelstring = "t = "..io.read()
local string2tab = loadstring(tabelstring)
string2tab()
local resultaat = selecteer_oneven(t)
printtabel(resultaat)

my input is

{ "aap", "kat", "hond", "paard", "kip", "salamander", "programmeren is leuk" }

and my output is

1   aap
2   hond
3   paard
4   salamander
5   programmeren is leuk

(sorry it is in Dutch)

"Aap", "Hond", "Programmeren is leuk" are the only uneven ones. "paard", and "salamander" are even.

Answer 1

Dont do table.remove on the table you are checking at same time.
Better do a second local table and insert q.
And finaly return the second table...

local function selecteer_oneven(tabel)
    local tabel2={}
    for q, n in ipairs(tabel) do
    if (q % 2) ~= 0 then
      table.insert(tabel2, q)
    end
  end
  return tabel2
end

...dont tested - yet ;-)

EDIT: Tested with lua -i

-- <ready>
>function selecteer_oneven(tabel)
    local tabel2={}
    for q, n in ipairs(tabel) do
    if (q % 2) ~= 0 then
      table.insert(tabel2, q)
    end
  end
  return tabel2
end
-- <ready>
>dump(selecteer_oneven({1,2,3,4,5,6,7,8,9,10}))
1=1
2=3
3=5
4=7
5=9
-- <ready>
>-- whats dump?
-- <ready>
>code.dump
-- dump()
return function(dump)
for key,value in pairs(dump) do
  io.write(string.format("%s=%s\n",key,value))
end
end
-- <ready>