How can i use console in C when doing graphics using SDL

Discussion in 'C Programming' started by smartbeginner, Sep 26, 2006.

  1. I cannot view in the console what all i have included in printf() .Why
    this?
    Code:
    #include<stdio.h>
    #include<conio.h>
    #include "SDL/SDL.h"
    int main(void)
    {
    int x=1;
    SDL_Event event;
    SDL_Init(SDL_INIT_JOYSTICK );
    SDL_Joystick *joy;
    // Check for joystick
    if(SDL_NumJoysticks()>0){
    // Open joystick
    joy=SDL_JoystickOpen(0);
    if(joy)
    {
    printf("Opened Joystick 0\n");
    printf("Name: %s\n", SDL_JoystickName(0));
    }
    SDL_Quit();
    SDL_JoystickClose(joy);
    return 0;
    }
     
    smartbeginner, Sep 26, 2006
    #1
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  2. In article <>,
    smartbeginner <> wrote:
    >I cannot view in the console what all i have included in printf() .Why
    >this?
    >Code:
    >#include<stdio.h>
    >#include<conio.h>
    >#include "SDL/SDL.h"


    Neither conio nor SDL are part of the C standard, so in this newsgroup
    we do not know what they do. In particular, as you have used <conio.h>
    instead of "conio.h" you would be picking up a conio.h from the
    implementation's headers, and the implementation might have done
    something stupid such as redefining printf().

    >int main(void)
    >{
    > int x=1;
    > SDL_Event event;
    > SDL_Init(SDL_INIT_JOYSTICK );
    > SDL_Joystick *joy;
    >// Check for joystick
    > if(SDL_NumJoysticks()>0){
    > // Open joystick
    > joy=SDL_JoystickOpen(0);
    > if(joy)
    > {
    > printf("Opened Joystick 0\n");
    > printf("Name: %s\n", SDL_JoystickName(0));
    >}
    >SDL_Quit();
    >SDL_JoystickClose(joy);
    > return 0;
    >}


    This is not your real code. This code would not compile. The { on
    the if(SDL_NumJoysticks()>0) line matches against the } after the
    return 0, and there is no matching } for the { that begins the routine.

    Notice that in your code, you only use printf() if you were able to
    open a Joystick (whatever that means.) The reason you do not get
    any output could be as simple as you not being able to open any
    joysticks.

    I question whether you should really be closing a joystick *after*
    you Quit SDL -- doesn't Quit mean "get out of SDL", after which
    point closing a joystick would not be valid?

    Your code does not use the int x, but that would not cause any problems.

    I note that your code is C99, not C89: you have a function call
    (to SDL_Init) before the declaration of SDL_Joystick *joy, which
    would not be valid in C89. The // comments are also not valid in C89
    but are a common extension. Please be aware that there are very few
    fully compliant "hosted" C99 implementations available, and it is fairly
    unlikely that you are using one of them. Because of the non-compliance
    of the environment, your code might do things that would not be expected
    according to the C99 standard, and there isn't much you can do about
    that except to study in detail exactly how your environment differs
    from a true C99 environment. It is safer to write in C89.


    Your code appears to have platform dependancies; in particular,
    it appears to be Windows specific code. After fixing the above code
    issues, if you continue to have difficulty, contact a newsgroup
    that deals with your platform.

    [Off topic]
    As you are using Windows, are you sure the console isn't simply being
    closed before you have a chance to read anything on it?
    --
    "It is important to remember that when it comes to law, computers
    never make copies, only human beings make copies. Computers are given
    commands, not permission. Only people can be given permission."
    -- Brad Templeton
     
    Walter Roberson, Sep 26, 2006
    #2
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  3. -cnrc.gc.ca (Walter Roberson) writes:
    [...]
    > I note that your code is C99, not C89: you have a function call
    > (to SDL_Init) before the declaration of SDL_Joystick *joy, which
    > would not be valid in C89. The // comments are also not valid in C89
    > but are a common extension. Please be aware that there are very few
    > fully compliant "hosted" C99 implementations available, and it is fairly
    > unlikely that you are using one of them. Because of the non-compliance
    > of the environment, your code might do things that would not be expected
    > according to the C99 standard, and there isn't much you can do about
    > that except to study in detail exactly how your environment differs
    > from a true C99 environment. It is safer to write in C89.


    Given that the program appears to be Windows-specific, and given
    Microsoft's apparent lack of interest in supporting C99, it's more
    likely that the OP is using a C++ compiler.

    --
    Keith Thompson (The_Other_Keith) <http://www.ghoti.net/~kst>
    San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
    We must do something. This is something. Therefore, we must do this.
     
    Keith Thompson, Sep 26, 2006
    #3
  4. smartbeginner

    jacob navia Guest

    smartbeginner wrote:
    > I cannot view in the console what all i have included in printf() .Why
    > this?
    > Code:
    > #include<stdio.h>
    > #include<conio.h>
    > #include "SDL/SDL.h"
    > int main(void)
    > {
    > int x=1;
    > SDL_Event event;
    > SDL_Init(SDL_INIT_JOYSTICK );
    > SDL_Joystick *joy;
    > // Check for joystick
    > if(SDL_NumJoysticks()>0){
    > // Open joystick
    > joy=SDL_JoystickOpen(0);
    > if(joy)
    > {
    > printf("Opened Joystick 0\n");
    > printf("Name: %s\n", SDL_JoystickName(0));
    > }
    > SDL_Quit();
    > SDL_JoystickClose(joy);
    > return 0;
    > }
    >


    To see the program output you should compile it as
    a console application or use the windows API to open a console
    under program control. Anyway, if you run it in a console window,
    you should see the output. stdout and stderr are not initialized
    correctly in windows applications since there is no "screen"
    where they should be redirected to.

    ANOTHER REAL POSSIBILITY is that obviously your
    SDL_JoystickOpen(0) call failed and you do not see
    anything because you did not consider the failure case

    Rewrite your code so that there is
    if (joy) {
    }
    else {
    printf("Did not work!\n");
    }
     
    jacob navia, Sep 26, 2006
    #4
  5. My original code.As you said I made this as a console project.But even then..

    /*
    Example is directly from the SDL documentation....
    The change made by me caused a console window to be opened
    But what all i wrote in printf() wasn't appearing
    I desperately tried fprintf() then also not working..
    How can I achieve my goal..
    Any tutorials or links giving the help
    */
    #include<stdio.h>
    #include "conio.h"
    #include "iostream.h"
    #include "SDL/SDL.h"
    const int WINDOW_WIDTH = 640;
    const int WINDOW_HEIGHT = 480;
    const char* WINDOW_TITLE = "SDL Start";

    int main(int argc, char **argv)
    {
    printf("\n Entering to code");
    fprintf(stdout,"Hi");
    int x=1;
    SDL_Event event;
    SDL_Init( SDL_INIT_VIDEO );
    SDL_Init(SDL_INIT_JOYSTICK );
    SDL_Surface* screen = SDL_SetVideoMode( WINDOW_WIDTH,
    WINDOW_HEIGHT, 0,
    SDL_HWSURFACE | SDL_DOUBLEBUF );
    SDL_WM_SetCaption( WINDOW_TITLE, 0 );
    SDL_Joystick *joy;

    if(SDL_NumJoysticks()>0){
    joy=SDL_JoystickOpen(0);

    if(joy)
    printf("Opened Joystick 0\n");
    else
    printf("Couldn't open Joystick 0\n");
    }

    while(x)
    {
    if (SDL_PollEvent(&event))
    {
    if(event.type==SDL_QUIT)
    x=0;
    if (event.type==SDL_KEYDOWN)
    {
    SDLKey keyPressed = event.key.keysym.sym;
    switch (keyPressed)
    {
    case SDLK_ESCAPE:
    x=0;
    break;
    }

    }
    }
    }
    SDL_Quit();
    SDL_JoystickClose(joy);
    printf("Can I now be active");
    return 0;
    }
     
    smartbeginner, Sep 27, 2006
    #5
  6. Re: My original code.As you said I made this as a console project.Buteven then..

    smartbeginner wrote:
    > /*
    > Example is directly from the SDL documentation....
    > The change made by me caused a console window to be opened
    > But what all i wrote in printf() wasn't appearing
    > I desperately tried fprintf() then also not working..
    > How can I achieve my goal..
    > Any tutorials or links giving the help
    > */

    I can think of two things to do:
    1. Ask in a forum that deals with SDL and/or Windows, as this newsgroup
    does not. Perhaps the SDL site have some pointers.

    2. Install a *nix variant, as there you can still output to a console
    when using SDL.
     
    =?ISO-8859-1?Q?=22Nils_O=2E_Sel=E5sdal=22?=, Sep 27, 2006
    #6
  7. Re: My original code.As you said I made this as a console project.Buteven then..

    Nils O. Selåsdal wrote:
    > smartbeginner wrote:
    >> /*
    >> Example is directly from the SDL documentation....
    >> The change made by me caused a console window to be opened
    >> But what all i wrote in printf() wasn't appearing
    >> I desperately tried fprintf() then also not working..
    >> How can I achieve my goal..
    >> Any tutorials or links giving the help
    >> */

    > I can think of two things to do:
    > 1. Ask in a forum that deals with SDL and/or Windows, as this newsgroup
    > does not. Perhaps the SDL site have some pointers.
    >
    > 2. Install a *nix variant, as there you can still output to a console
    > when using SDL.

    Oh, there's a 3. workaround way too.
    freopen stdout to a file, and look at the file rather than a console.
    Or redirect stdout to a file by other means
     
    =?ISO-8859-1?Q?=22Nils_O=2E_Sel=E5sdal=22?=, Sep 27, 2006
    #7
  8. smartbeginner

    Nelu Guest

    Re: My original code.As you said I made this as a console project.Buteven then..

    Nils O. Selåsdal wrote:
    > smartbeginner wrote:
    >> /*
    >> Example is directly from the SDL documentation....
    >> The change made by me caused a console window to be opened
    >> But what all i wrote in printf() wasn't appearing
    >> I desperately tried fprintf() then also not working..
    >> How can I achieve my goal..
    >> Any tutorials or links giving the help
    >> */

    > I can think of two things to do:
    > 1. Ask in a forum that deals with SDL and/or Windows, as this newsgroup
    > does not. Perhaps the SDL site have some pointers.
    >
    > 2. Install a *nix variant, as there you can still output to a console
    > when using SDL.


    <OT>
    I believe the Windows API allows you to attach a console to an
    application if it detached at execution. Clearly, a better answer
    can only come from a Windows group.
    </OT>

    --
    Ioan - Ciprian Tandau
    tandau _at_ freeshell _dot_ org (hope it's not too late)
    (... and that it still works...)
     
    Nelu, Sep 27, 2006
    #8
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