Decode binaries in C linked-in driver

Cosmin Gheorghita <>
Sat Jul 31 02:37:01 CEST 2004

Hello to everyone. 

I have the following problem with Erlang: I need to read a file that contains integers
from Erlang and send it to a linked-in driver written in VC++. Here is my code:
F = "fis.txt",
case file:open(F, [read, raw, binary]) of
	{ok, FHandler} ->
	io:format("The file ~p was successfully opened ~n", [FHandler]),
	case file:read_file(F) of
		{ok, Bin} ->
			io:format("~nBin file read:~n ~w~n", [floating(Bin)]),
			call_port({testF, Bin}),
			io:format("~nBin file ok~n");
		{error, Reason} ->
			io:format("~nBig error while reading the file: ~p~n", [Reason])
The data is sent by:	Port ! {self(), {command, encode(Msg)}},
and encode() looks like this: encode({testF, LBin}) -> [4, LBin].

Now on the C part, the code is as follows:
	} else if (fn == 4) {
		index = 0;
		f_temp = fopen("fis_temp.txt", "wt");
		fprintf(f_temp, "%d\n", bufflen);
		ei_get_type(buff, &index, &type, &size);
		fprintf(f_temp, "%d - %d\n", type, size);
		ei_decode_binary(buff, &index, (void*) dec_buff, &bufflen);

		for(i = 0;i < bufflen;i++) {
			fprintf(f_temp, "%d\n", dec_buff[i]);

The dec_buff[] array is all full of 0's (I allocated mem with calloc())... Reading
directly from buff[] doesn't work either..
All I want for the beginning is to read a file from Erlang and be able to write it back
using fprinf(f, %d%, ...). So I want to decode the binaries into integers. Any idea on

Thank you in advance,

P.S. I am a total beginner in Erlang, so pls be as explicit as possible

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