How to print directly from compile screen?

This is a discussion on How to print directly from compile screen? within the C Programming forums, part of the General Programming Boards category; Originally Posted by matsp If it's a console appliction (in Windows), you can open "lpt:" as a file [for writing]: ...

  1. #16
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    Quote Originally Posted by matsp View Post
    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"?

  2. #17
    Frequently Quite Prolix dwks's Avatar
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    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
    dwk

    Seek and ye shall find. quaere et invenies.

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  3. #18
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    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?

  4. #19
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    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
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  5. #20
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    Okay, so
    Code:
    flpt = fopen("lpt1:", "w");
    fixes that problem, right? Now, what would I do to tell the printer to print?

  6. #21
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    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
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  7. #22
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    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

  8. #23
    Frequently Quite Prolix dwks's Avatar
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    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.
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell


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  9. #24
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    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.

  10. #25
    Frequently Quite Prolix dwks's Avatar
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    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.
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell


    Other boards: DaniWeb, TPS
    Unofficial Wiki FAQ: cpwiki.sf.net

    My website: http://dwks.theprogrammingsite.com/
    Projects: codeform, xuni, atlantis, nort, etc.

  11. #26
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    So I have to scrap my whole thing?

  12. #27
    Frequently Quite Prolix dwks's Avatar
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    Not necessarily. You could create a file at first, and then if you figure out how to print directly, implement that instead . . . .
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell


    Other boards: DaniWeb, TPS
    Unofficial Wiki FAQ: cpwiki.sf.net

    My website: http://dwks.theprogrammingsite.com/
    Projects: codeform, xuni, atlantis, nort, etc.

  13. #28
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    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.

  14. #29
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    So what DO YOU have at the moment?

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  15. #30
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    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.

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