Re: Writing a file to /dev/lp0 in c++

From:

=?ISO-8859-1?Q?Erik_Wikstr=F6m?= <Erik-wikstrom@telia.com>

Newsgroups:

comp.lang.c++

Date:

Fri, 14 Sep 2007 13:23:17 GMT

Message-ID:

<9XvGi.8718$ZA.4492@newsb.telia.net>

On 2007-09-14 13:40, MAx wrote:

Hi guys,
I am a c++ newbee and i am trying to write a file to a default
printer.
Please have a look at the code below and let me know if it'll work.

I know that similar code in C will work.
I was wondering how will the associated driver react.....

#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    char buffer[50];
    ifstream inFile("print_data.txt", ios::in);
    ofstream outFile("/dev/lp0",ios::out);

No need to specify ios::in or ios::out.

     if (!inFile){
    cout << "Unable to open the file, print_data.txt"<< endl;
    return 1;
    }

    if(!outFile){
    cout << "Unable to open file, /dev/lp0" << endl;
    return 1;
    }

    while (inFile >> buffer) // Copying data from text file
    outFile << buffer; // Writing data to the Device file

Don't think that is a good idea. The stream have no idea how much it
should read for each iteration of the loop. I would probably use either
read() and write(), or use std::copy() together with stream iterators
(untested):

#include <algorithm>
#include <fstream>
#include <iterator>

int main()
{
    std::ifstream in("test.txt");
    std::ofstream out("out.txt");

    std::istream_iterator<char> inIt(in);
    std::istream_iterator<char> endIt;
    std::ostream_iterator<char> outIt(out);

    std::copy(inIt, endIt, outIt);
}

--
Erik Wikstr?m