[eluser]sophistry[/eluser]
ok, sorry... there are a few problems still with the regex approach. the variable $line is misleading because it actually has a file name in it and not a line. you have to add
file_get_contents($line)
inside the loop to be able to get the file contents and parse those strings...
BUT........
i'm going to go back to my original post and say that you should just load up all the helpers in the helpers dir (i saw some nice code in your previous thread that seems to work).
then if the function you are looking for exists, function_exists() returns true.
doing all this string parsing with helper files seems counterproductive. i still don't understand why it is necessary.
take a step back from the problem, read the CI manual (there is one in spanish en caso de que necesites)