Send raw data to printer programmatically - c++

Question

I want to send to my printer data I load from a file so that it can print a barcode (ITF 2/5).
if I use the command prompt and do "print c:\test lpt1", it works like a charm and it prints the expected barcode. However, when I try to do this programmatically, the printer fails to provide said barcode. Readable text works fine, it's (so far) exclusively an issue I have with the barcode printing.
I have the following code in which ( I thought ) I would be sending a printer raw data (not rendered in any way) so that the printer can decide how to decode those bytes I'm sending to it.
std::FILE* fd = fopen("c:\\test", "rb");
std::fseek(fd, 0L, SEEK_END);
int size = std::ftell(fd);
std::fseek(fd, 0L, SEEK_SET);
int beginning = std::ftell(fd);
if(fd == NULL)
{
std::cerr << "Error opening file\n";
return;
}
char* buffer = (char*)malloc(size);
std::fread(buffer, 1, size, fd);
std::ofstream output("lpt1", std::ios_base::out);
output << buffer;
My only guess (and a blind one, at that) is that I am mistakingly assuming the ofstream is receiving raw data when it's not... and I don't know why or how to solve that.
I am not asking for a 'do my homework for me' answer (Although a very clear and epic answer would be awesome) but at least if you could point me in the right way of why I am not getting the expected result, I would be really grateful. Even some keywords for searching and researching on my own would be great, too. I honestly have no idea of what I am doing wrong.
This is some new code I tried because of a suggestion to use IOStreams, again, I get NOT the desired result when I try to edit the content of input.rdbuf().
static void ImprimirArchivo(unsigned char* path)
{
std::ifstream input((char*)path, std::ios::binary);
std::ofstream output("lpt1", std::ios::binary);
std::istreambuf_iterator<char> eos;
std::istreambuf_iterator<char> streamInputIterator (input.rdbuf());
bool codeBarStarted = false;
int iterationsCounter = 0;
while(streamInputIterator!=eos)
{
if(*streamInputIterator == 0x14)
{
output << '1d';
output << '6b';
output << '05';
output << '30';
codeBarStarted = true;
}
else
{
output << *streamInputIterator;
}
if(codeBarStarted)
{
iterationsCounter++;
if(iterationsCounter == 10)
{
output << 0x00;
codeBarStarted = false;
iterationsCounter = 0;
}
}
streamInputIterator++;
}
Please note that when I do
if(*streamInputIterator == 0x14)
{
output << '1d';
output << '6b';
output << '05';
codeBarStarted = true;
}
If I replace that with
if(*streamInputIterator == 0x14)
{
output << 0x1d;
output << 0x6b;
output << 0x05;
codeBarStarted = true;
}
the corresponding output is still wrong, but wholly different. When I use 0xXY, what's printed is the decimal number as in: output << 0x1d makes the printer print "29" (text).

Answer 1

A short in the dar: Open both files in binary mode, in particular std::ofstream:
std::ofstream output("lpt1", std::ios::binary);
(there is no need to also specify std::ios::out because it is added when opening a std::ofstream anyway but you could use std::ios::out | std::ios_binary if you want).
Personally, I would use IOStreams for both the input and the output:
std::ifstream input("c:\\test", std::ios::binary);
if (input) {
std::ofstream("lpt1", std::ios::binary) << input.rdbuf();
}
else {
std::cerr << "ERROR: failed to open 'c:\\test' for reading\n";
}