Using standard printing from windows

Tuesday Jun 29th 1999 by Richard Warg

Using standard printing from windows

There are many applications where I don't really want to use the usual windows page print. Instead I want output to go directly to the printer using standard print i/o. It's actually a topic that is hard to find in any of the books on Windows, at least I've never found anything on it. But to my surprise I recently learned that standard (DOS/UNIX) printing is alive and well underneath windows. All we need to do is open a printer port and print to it.

If the printer is directly attached to the computer it's trivial. The method for obtaining a printer port when the printer is on the network isn't hard either.

The example below shows how I use the Windows NET USE command to re-direct LPT1 to a shared printer on an NT Server. The same technique applies for Novell networks with a slightly different syntax.

Try this out by creating a new MFC Form-based project. Put a button on the form and attach this code to it. You can actually print with only 3 lines of code:

        FILE *fp = fopen("LPT1", "w");
        fprintf(fp,"What's up, Doc?\n");

Instant print gratification!!

While the program is open it hogs the printer port. In my shop that isn't a problem but be aware of the effect on your windows spooled output.

                        THE CODE

// the headers for the conventional i/o routines

using namespace std;      // makes string and ofstream
                          // work without std:: qualifier

void CLineprtView::OnButton1()
    // I could have used a CString instead of the buff[]
    // but I wanted to show how this is used with lightweight
    // ATL code and STD library
    char buff[MAX_BUFF_SIZE];
    // My printer is located on another server so I must re-direct the
    // printer port.  If the printer is directly attached this extra step
    // is not needed.
    // on my network the printer is published as \\GREEN\hp5annex
    // All those back-slashes escape the backslash in the path name
        system("NET USE LPT1 /d");  // free up the port
        system("net use lpt1 \\\\green\\hp5annex");
    // old fashioned file handle with
    // old fashioned open of the printer port
    FILE *ptr = fopen("LPT1","w");
    // laser printer setup string
    // old fashioned print
    fprintf(ptr,"Who of late doth make a thimble.\n");
    fprintf(ptr,"Is a lower bunk a status symbol??\n");
    // old fashioned close
    // now the same thing with stream io
    ofstream optr("LPT1", ios::out);
    string str_text = "Hey Doc, Ain't this a print test from windows\n";
    str_text += "with more lines to follow?\n";

    optr << str_text << endl;
    optr << "Quiet, wabbit. I'm conversing with my muse!!\n";
    optr << "That's all folks." << "\f" << flush;     // add a formfeed
    // the printer connection is still open so close it
    // drop the network link
        system("net use lpt1 /d");

In practice I get printer path information from the registry on each machine, so the real live code is a little busier than this example, but not much.

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