Question

Trying to cut a Line, read from a file, into a list of strings. This causes always a exception i don’t know to solve.

    exception error: no function clause matching string:tokens1
(<<"Cascading Style Sheets CSS are an increasingly common way for website developers to control the look\n">>," ,.",[]) in function  readTest:run/1



-module(readTest).
-export([run/1]).

open_file(FileName, Mode) ->
    {ok, Device} = file:open(FileName, [Mode, binary]),
    Device.

close_file(Device) ->
    ok = file:close(Device).

read_lines(Device, L) ->
    case io:get_line(Device, L) of
        eof ->
            lists:reverse(L);
        String ->
            read_lines(Device, [String | L])
    end.

run(InputFileName) ->
    Device = open_file(InputFileName, read),
    Data = read_lines(Device, []),
    close_file(Device),
    io:format("Read ~p lines~n", [length(Data)]),
    Bla = string:tokens(hd(Data)," ,."),
    io:format(hd(Data)).

May its an easy failure. getting just started in erlang.

Answer 1

When you open a file with binary flag, lines are read as binaries rather than lists (strings).
So in your code

 Bla = string:tokens(hd(Data)," ,."),

hd(Data) is actually a binary, which causes string:tokens to crash.
You could either remove binary flag from file:open, or convert binary to list explicitly:

 Bla = string:tokens(binary_to_list(hd(Data))," ,."),