By using this site, you agree to our updated Privacy Policy and our Terms of Use. Manage your Cookies Settings.
446,406 Members | 954 Online
Bytes IT Community
+ Ask a Question
Need help? Post your question and get tips & solutions from a community of 446,406 IT Pros & Developers. It's quick & easy.

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

P: n/a
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;
}

Sep 26 '06 #1
Share this Question
Share on Google+
7 Replies


P: n/a
In article <11**********************@e3g2000cwe.googlegroups. com>,
smartbeginner <rr******@gmail.comwrote:
>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
Sep 26 '06 #2

P: n/a
ro******@ibd.nrc-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) ks***@mib.org <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.
Sep 26 '06 #3

P: n/a
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");
}
Sep 26 '06 #4

P: n/a
/*
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;
}

Sep 27 '06 #5

P: n/a
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.
Sep 27 '06 #6

P: n/a
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
Sep 27 '06 #7

P: n/a
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...)
Sep 27 '06 #8

This discussion thread is closed

Replies have been disabled for this discussion.