I little hint please...

F34R · Post by **F34R** » Sun May 21, 2006 7:12 am

Just started to learn C, and I wanted to start very simple. What I thought wouldnt be too difficult, has turned into a hair pulling nightmare for a n00b. I would appreciate a hint on this, I'm not really looking for an exact answer here. Just a hint where I've went wrong. Here is the code:

Code: Select all

#include <pspkernel.h>
#include <pspdisplay.h>
#include <pspctrl.h>
#include <stdio.h>
#include "graphics.h"
#include "callback.h"

PSP_MODULE_INFO&#40;"Homework", 0, 1, 1&#41;;

#define RGB&#40;r, g, b&#41; &#40;&#40;r&#41;|&#40;&#40;g&#41;<<16&#41;|&#40;&#40;b&#41;<<16&#41;&#41;


int main&#40;&#41; &#123;

          SetupCallbacks&#40;&#41;;
          initGraphics&#40;&#41;;
          SceCtrlData pad;
          int goodScore;
          int badScore;
          Color white = RGB&#40;255,255,255&#41;;
          Color green = RGB&#40;0,255,0&#41;;
          char PrintScoreG&#91;200&#93;;

          for&#40;;;&#41; &#123;
          goodScore = 0;
          badScore = 0;
          printTextScreen&#40;20, 5, "Can you add ?", white&#41;;
          printTextScreen&#40;20, 15, "Coded By F34R", white&#41;;
          printTextScreen&#40;10, 40, "1 + 1 =", white&#41;;
          printTextScreen&#40;10, 60, "CROSS&#58; 0", white&#41;;
          printTextScreen&#40;10, 70, "SQUARE&#58; 3", white&#41;;
          printTextScreen&#40;10, 80, "TRIANGLE&#58; 21", white&#41;;
          printTextScreen&#40;10, 90, "CIRCLE&#58; 2", white&#41;;

             sceCtrlReadBufferPositive&#40;&pad, 1&#41;;
             if&#40;pad.Buttons & PSP_CTRL_CROSS&#41; &#123;
                printTextScreen&#40;10,120, "CORRECT", green&#41;;
                goodScore++;
                printTextScreen&#40;10, 150, "This program will exit now.", white&#41;;
                break;
             &#125;
             if&#40;pad.Buttons & PSP_CTRL_SQUARE&#41; &#123;
               printTextScreen&#40;10,120, "INCORRECT", green&#41;;
               goodScore--;
             &#125;
             if&#40;pad.Buttons & PSP_CTRL_TRIANGLE&#41; &#123;
               printTextScreen&#40;10,120, "INCORRECT", green&#41;;
               goodScore--;
             &#125;
             if&#40;pad.Buttons & PSP_CTRL_CIRCLE&#41; &#123;
               printTextScreen&#40;10,120, "INCORRECT", green&#41;;
               goodScore--;
             &#125;

          sprintf&#40;PrintScoreG, " Correct &#58; %i", goodScore&#41;;
          printTextScreen&#40;10, 200, PrintScoreG, green&#41;;
          flipScreen&#40;&#41;;
          &#125;
sceKernelExitGame&#40;&#41;;
return 0;
&#125;

That is supposed to display a question, and respond when the user presses a button. Any help would be appreciated. I'd like to learn why it doesnt work, so I'd like a hint please. Thanks for your time.

ReKleSS · Post by **ReKleSS** » Sun May 21, 2006 9:08 am

It would help if you actually explained why it doesn't work, i.e. what happens and what goes wrong. After looking over it quickly, I don't see anything problematic in the code you've given.
-ReK

Jim · Post by **Jim** » Sun May 21, 2006 9:48 am

If it's C, it won't compile. This is the second time I've seen this

Code: Select all

int main&#40;&#41; &#123; 
          SetupCallbacks&#40;&#41;; 
          initGraphics&#40;&#41;; 
          SceCtrlData pad;

this week.
In C you must declare all your variables before calling any functions, ie.

Code: Select all

int main&#40;&#41; &#123; 
          SceCtrlData pad;
          SetupCallbacks&#40;&#41;; 
          initGraphics&#40;&#41;;

Jim

F34R · Post by **F34R** » Sun May 21, 2006 12:13 pm

It compiles without any warnings or errors. When I run it on the PSP, the only text I see is the output from:

Code: Select all

sprintf&#40;PrintScoreG, " Correct &#58; %i", goodScore&#41;;
          printTextScreen&#40;10, 200, PrintScoreG, green&#41;;

Nothing happens at all if I press any buttons. If I use Home > yes to exit, it crashes the PSP, and it powers itself off.

After looking at what the poster above said about decalaring variables before calling functions, I changed it. Now it actually works. Thanks. I didnt realize that, and now I've learned.... thank you very much.

On a side note, it did compile the other way though lol.

moonlight · Post by **moonlight** » Sun May 21, 2006 3:08 pm

Jim wrote:If it's C, it won't compile. This is the second time I've seen this
Code: Select all
int main&#40;&#41; &#123; 
          SetupCallbacks&#40;&#41;; 
          initGraphics&#40;&#41;; 
          SceCtrlData pad;
this week.
In C you must declare all your variables before calling any functions, ie.
Code: Select all
int main&#40;&#41; &#123; 
          SceCtrlData pad;
          SetupCallbacks&#40;&#41;; 
          initGraphics&#40;&#41;; 
Jim

Incorrect. That changed in the new C standard of 1999 if i don't remember bad. Since that, variables can be declared in whatever part of the function.

Post by **Drakonite** » Sun May 21, 2006 3:19 pm

moonlight wrote:
Jim wrote:If it's C, it won't compile. This is the second time I've seen this
Code: Select all
int main&#40;&#41; &#123; 
          SetupCallbacks&#40;&#41;; 
          initGraphics&#40;&#41;; 
          SceCtrlData pad;
this week.
In C you must declare all your variables before calling any functions, ie.
Code: Select all
int main&#40;&#41; &#123; 
          SceCtrlData pad;
          SetupCallbacks&#40;&#41;; 
          initGraphics&#40;&#41;; 
Jim
Incorrect. That changed in the new C standard of 1999 if i don't remember bad. Since that, variables can be declared in whatever part of the function.

Erm.. Incorrrect! .. while C99 does in fact change that, it's still against the old ansi C rules, which many compilers (gcc for one IIRC) default to unless you specify otherwise.

moonlight · Post by **moonlight** » Sun May 21, 2006 3:32 pm

Drakonite wrote:
moonlight wrote:
Jim wrote:If it's C, it won't compile. This is the second time I've seen this
Code: Select all
int main&#40;&#41; &#123; 
          SetupCallbacks&#40;&#41;; 
          initGraphics&#40;&#41;; 
          SceCtrlData pad;
this week.
In C you must declare all your variables before calling any functions, ie.
Code: Select all
int main&#40;&#41; &#123; 
          SceCtrlData pad;
          SetupCallbacks&#40;&#41;; 
          initGraphics&#40;&#41;; 
Jim
Incorrect. That changed in the new C standard of 1999 if i don't remember bad. Since that, variables can be declared in whatever part of the function.
Erm.. Incorrrect! .. while C99 does in fact change that, it's still against the old ansi C rules, which many compilers (gcc for one IIRC) default to unless you specify otherwise.

Oh i see. You are right. I thought that gcc followed by default the C99 since it lets me declare the variables in whatever part and it doesn't give me any errors.
Any ideas why gcc let to do that if not specyfing the C99 standard?

Post by **Drakonite** » Sun May 21, 2006 3:50 pm

moonlight wrote: Oh i see. You are right. I thought that gcc followed by default the C99 since it lets me declare the variables in whatever part and it doesn't give me any errors.
Any ideas why gcc let to do that if not specyfing the C99 standard?

Well, I suppose it might not be using the old strict ansi C by default then... It might be using lax rules or might be even be defaulting to C99... TBH I'm not sure what standard newer gcc's default to.

cheriff · Post by **cheriff** » Sun May 21, 2006 4:14 pm

from the gcc manpage:

Code: Select all

gnu89
     Default, ISO C90 plus GNU extensions &#40;including some C99 fea-
     tures&#41;

I'm guessing free mixing of declarations and code is one of the c99 features included :)

Post by **ooPo** » Sun May 21, 2006 4:53 pm

Code: Select all

gcc -std=c99

Simple!

groepaz · Post by **groepaz** » Sun May 21, 2006 5:31 pm

ofcourse you should use

Code: Select all

gcc --ansi --strict --pedantic

damn newschoolers :o)

F34R · Post by **F34R** » Mon May 22, 2006 12:06 am

Here is the code once more. It works fine except that the score at the bottom isn't updated when the correct answer is chosen.

Code: Select all

#include <pspkernel.h>
#include <pspdisplay.h>
#include <pspctrl.h>
#include <stdio.h>
#include "graphics.h"
#include "callback.h"

PSP_MODULE_INFO&#40;"Homework", 0, 1, 1&#41;;

#define RGB&#40;r, g, b&#41; &#40;&#40;r&#41;|&#40;&#40;g&#41;<<8&#41;|&#40;&#40;b&#41;<<16&#41;&#41;


int main&#40;&#41; &#123;

          SceCtrlData pad;
          int goodScore;
          int badScore;
          int i;
          Color white = RGB&#40;255,255,255&#41;;
          Color green = RGB&#40;0,255,0&#41;;
          char PrintScoreG&#91;50&#93;;
          SetupCallbacks&#40;&#41;;
          initGraphics&#40;&#41;;


          for&#40;;;&#41; &#123;
          goodScore = 0;
          badScore = 0;
          printTextScreen&#40;20, 5, "Can you add ?", white&#41;;
          printTextScreen&#40;20, 15, "Coded By F34R", white&#41;;
          printTextScreen&#40;10, 40, "1 + 1 =", white&#41;;
          printTextScreen&#40;10, 60, "CROSS&#58; 0", white&#41;;
          printTextScreen&#40;10, 70, "SQUARE&#58; 3", white&#41;;
          printTextScreen&#40;10, 80, "TRIANGLE&#58; 21", white&#41;;
          printTextScreen&#40;10, 90, "CIRCLE&#58; 2", white&#41;;

          sceCtrlReadBufferPositive&#40;&pad, 1&#41;;

             if&#40;pad.Buttons & PSP_CTRL_CIRCLE&#41; &#123;
                printTextScreen&#40;10,120, "CORRECT", green&#41;;
                goodScore++;
                printTextScreen&#40;10, 150, "Press Start to exit.", white&#41;;

             &#125;
          sprintf&#40;PrintScoreG, " Correct &#58; %i", goodScore&#41;;
          printTextScreen&#40;10, 200, PrintScoreG, green&#41;;
             flipScreen&#40;&#41;;
             for&#40;i=0; i<1; i++&#41; &#123;
                              sceDisplayWaitVblankStart&#40;&#41;;
                    &#125;


          if&#40;pad.Buttons & PSP_CTRL_START&#41; &#123;
            break;
          &#125;
          &#125;
          

sceKernelExitGame&#40;&#41;;
return 0;
          &#125;

adrahil · Post by **adrahil** » Mon May 22, 2006 3:56 am

Code: Select all

          for&#40;;;&#41; &#123;
          goodScore = 0;
//
//&#91;...&#93;
//
             if&#40;pad.Buttons & PSP_CTRL_CIRCLE&#41; &#123;
                printTextScreen&#40;10,120, "CORRECT", green&#41;;
                goodScore++;
                printTextScreen&#40;10, 150, "Press Start to exit.", white&#41;;

             &#125;
//
//&#91;...&#93;
//
          &#125;

Uhm, I might not be an expert in C, but don't you always initialise that variable to 0 at each loop?

dot_blank · Post by **dot_blank** » Mon May 22, 2006 8:58 am

that is correct