[LUA] New to lua, confused about handling of numerical strings

Hello folks. I'm about a week in to CC and Lua, having a problem I don't understand.

I'm trying to loop through a text file of computerIDs (to send the same command to multiple machines over rednet).

Everything I've read says Lua converts numbers and strings invisibly, but when I use the result of fs.readLine() in rednet.send I get a string error.

The turtleIDs file is just one ID per line:
50
48
…
etc

Example:

idFile = fs.open("miningTurtleIDs","r")
while true do
  turtleID = idFile.readLine()
  if turtleID == nil then break end
  print(turtleID)
  rednet.send(turtleID,"blappity blah")
end
idFile.close()

Returns:
50
rednet:53: Expected number

If I remove the rednet.send(), it sucessfully prints the numbers.

So far I can see that string.byte will do this, but seems complicated to implement for multi-digit numbers. I have a hunch I'm missing something basic about the language here, so asking the pros :)/>/>

Any help would be great. Also I know the while true loop is poor logic, but lets call this an alpha.

Split into new topic.

You're looking for tonumber(). Simply tonumber your numeric string and use the return value, which will be a number, or nil if the string was non-numeric.

I knew it had to be something simple. I read the lua docs for hours and didn't catch this. Facepalm, etc.

Thanks a mint, I'm off and runnin'