reading file whole flat text file to an array - erlang

Question

Im working with erlang writing an escript and Ive seen many examples with file io, not so easy to follow so i found this:
Text = file:read_file("f.txt"),
io:format("~n", Text).
works somehow, it does print the file contents followed by multiple errors
in call from erl_eval:do_apply/6 (erl_eval.erl, line 572)
in call from escript:eval_exprs/5 (escript.erl, line 850)
in call from erl_eval:local_func/5 (erl_eval.erl, line 470)
in call from escript:interpret/4 (escript.erl, line 768)
in call from escript:start/1 (escript.erl, line 277)
in call from init:start_it/1 (init.erl, line 1050)
in call from init:start_em/1 (init.erl, line 1030)
so what would be the easiest way to read the whole file and store the contents in an array or list for later use?

Answer 1

First, file:read_file/1 will return {ok, Binary} on success, where Binary is a binary representing the contents of the file. On error, {error, Reason} is returned. Thus your Text variable is actually a tuple. The easy fix (crashing if there is an error):
{ok, Text} = file:read_file("f.txt")
Next, the first argument to io:format/2 is a format string. ~n is a format that means "newline", but you haven't given it a format that means anything else, so it's not expecting Text as an argument. Furthermore, all arguments to the format string should be in a list passed as the second argument. ~s means string, so:
io:format("~s~n", [Text])
will print out the entire file, followed by a newline. If you want to pass multiple arguments, it would look something like:
io:format("The number ~B and the string ~s~n", [100, "hello"])
Notice how there are only two arguments to io:format/2; one just happens to be a list containing multiple entries.

Answer 2

Since your question asked for an easy way to read the contents of a file into a data-structure, you might enjoy file:consult/1. This solution assumes, you have control over the format of the file since consult/1 expects the file to consist of lines terminated with '.'. It returns {ok, [terms()]} | {error,Reason}.
So, if your file, t.txt, consisted of lines terminated by '.' as follows:
'this is an atom'.
{person, "john", "smith"}.
[1,2,3].
then you could utilize file:consult/1
1> file:consult("c:\t.txt").
2> {ok,['this is an atom',{person,"john","smith"},[1,2,3]]}