How to print directly from compile screen?

**mcotter222** · 03-19-2008

Originally Posted by matsp

If it's a console appliction (in Windows), you can open "lpt:" as a file [for writing]:

Code:

  FILE *flpt;
  flpt = fopen("lpt:", "w");
  if (flpt == NULL) { 
     perror("open LPT:"); 
     exit(1); 
  }
...

Then use "flpt" as your destination file.

--
Mats

I tryed this, but exit was undefined. Also, what do you mean when you say "Then use "flpt" as your destination file"?

**dwks** · 03-19-2008

exit is defined in <stdlib.h>, so make sure you #include that header file.

Also, what do you mean when you say "Then use "flpt" as your destination file"?

matsp meant that after that code has executed, the FILE stream flpt has been opened, and you can write to it. For example:

Code:

fprintf(flpt, "This goes to the printer.\n");

And, of course, everything printed to this file stream gets send to the printer. Theoretically.

You could also try the non-standard stdprn, although I hear it doesn't exist under MSVC. http://www.thescripts.com/forum/thread218908.html

**mcotter222** · 03-27-2008

Sorry to bring up old news guys, but I finally got a hold of a computer with a printer. I coded this, and nothing happened:

Code:

#include <stdio.h>
#include <stdlib.h>

int main()
{
  FILE *flpt;
  flpt = fopen("lpt:", "w");
  if (flpt == NULL) { 
     perror("open LPT:"); 
     exit(1); 
  }
  fprintf(flpt, "Test print.\n\nTest print.\n\nTest print.\n\n");
}

Missing anything?

**matsp** · 03-27-2008

Actually, you may need to use "LPT1:" (or some other number after LPT and before

.

Also, some printers need special instructions to tell it to print things (e.g. a postscript printer will most likely not do anything meaningfull if you just send some text to it).

--
Mats

**mcotter222** · 03-28-2008

Okay, so

Code:

flpt = fopen("lpt1:", "w");

fixes that problem, right? Now, what would I do to tell the printer to print?

**matsp** · 03-28-2008

How is the printer connected to your machine?
What printer is it?

It's highly likely that a USB printer will not respond to "LPT1:", for example.

--
Mats

**mcotter222** · 03-28-2008

It has to be functional on any printer. I test it with a USB printer, so what number do you suggest if not 1, or do I not even use a number?
Thanks
-Matt

**dwks** · 03-28-2008

If you want it to work on any printer, don't do it yourself. Use the operating system. It will have drivers for every printer that works with the system. An easy way to do this would be to output to a file, and have the user print this file. I'm sure this could be arranged with a system() call if you wanted to do it automatically.

Plus, I would find a program that printed something every time it was executed rather annoying.

**mcotter222** · 03-28-2008

I need it to print by itself every time. If that isn't possible to do on more than one printer, I guess I could find out what kind.

**dwks** · 03-28-2008

Your best bet in that case is to use a command line utility, in my opinion. Perhaps one of these will help.
http://www.google.ca/search?hl=en&q=...e+Search&meta=
http://www.robvanderwoude.com/2kprintcontrol.html

I found out that XP has a "print" command. http://www.ss64.com/nt/print.html
It looks like it just uses LPT1, though.

It might help to know what printer you have.

**mcotter222** · 03-28-2008

So I have to scrap my whole thing?

**dwks** · 03-29-2008

Not necessarily. You could create a file at first, and then if you figure out how to print directly, implement that instead . . . .

**mcotter222** · 04-03-2008

Ok, so, I am a complete beginner, to accessing other files. I barely understand how what I have works. I hate to do it, but I need to ask for help on that one.

**matsp** · 04-04-2008

So what DO YOU have at the moment?

--
Mats

**mcotter222** · 04-06-2008

I have:

Code:

#include <stdio.h>
#include <stdlib.h>

int main()
{
  FILE *flpt;
  flpt = fopen("lpt:1", "w");
  if (flpt == NULL) { 
     perror("open LPT:"); 
     exit(1); 
  }
  fprintf(flpt, "Test print.\n\nTest print.\n\nTest print.\n\n");
}

And I know that system() might help, but I have no idea what that does.