table.unserialize(table) not working

Here is my code:

  function readFile(name)
  local f = fs.open(name,"r")
local data = f.readAll()
f.close()
return textutils.unserialize(data)
end
function editFile(fileName,string,line)
if fileName == nil or string == nil then
  error("String expected got nil")
elseif fileName ~= tostring(fileName) or string ~= tostring(string) then
  error("String expected as file name got number")
else
data ={}
  data = readFile(fileName)
  if line == nil then
   table.insert(data, string)
  elseif line ~= tonumber(line) then
   error("Number expected as line, got string.")
  else
   table.insert(data, line, string)
  end
  print(data)
end
end

I run the function and it all works, but i get a string instead of a table, so i cannot add my var string to it using table.insert()

Split into new topic.

Please paste the file you are trying to edit with this script.

As Lyqyd already said, give us more information concerning the file you open.
Apart from your title, you could clean up your programm a little:

if fileName ~= tostring(fileName) then
--Could be
if type(fileName) ~= "string" then

if fileName == nil then
--Could be
if not fileName then --nil will be interpretated as false, anything else as true

if line ~= tonumber(line)
--Could be
if type(line) ~= "number" then

And finally: I wouldn't recommend using string as name for a string variable. I don't know if it is used by lua, but since notepad++ and the [.code] script will color it different I'm guessing it is. :P/>

I hope this might help you as well… :D/>

Yes, the variable name "string" is used by the string library.