C/C++ Programming Help Thread

[Archaemic]

Well, what are the errors?

[MiG]

Well, what are the errors?

$ make
psp-gcc -I. -I/usr/local/pspdev/psp/sdk/include -O2 -G0 -Wall -D_PSP_FW_VERSION=
150   -c -o main.o main.c
main.c: In function 'main':
main.c:31: error: syntax error before '&' token
main.c: At top level:
main.c:57: error: syntax error before '&' token
main.c: In function 'FPS':
main.c:59: error: 'fps' undeclared (first use in this function)
main.c:59: error: (Each undeclared identifier is reported only once
main.c:59: error: for each function it appears in.)
main.c:60: error: 'fpsTickNow' undeclared (first use in this function)
main.c:62: error: 'fpsTickLast' undeclared (first use in this function)
main.c:62: error: 'tickResolution' undeclared (first use in this function)
main.c:65: error: 'fpsDisplay' undeclared (first use in this function)
make: *** [main.o] Error 1

Below is the whole code for the project (Yes i know it does pretty much sod all right now but I just need to set the basics up and get everything moving).

#include <malloc.h>						//For memalign()
#include <pspkernel.h>
#include <pspdisplay.h>
#include <pspdebug.h>
#include <stdio.h>
#include <pspcallbacks.h>
#include <pspgu.h>
#include <pspgum.h>
#include <psprtc.h>						// for the timer/fps functions
#include "graphics.h"

#define BUF_WIDTH  (512)
#define SCR_WIDTH  (480)
#define SCR_HEIGHT (272)

PSP_MODULE_INFO("Breakout", 0, 1, 1);
PSP_MAIN_THREAD_ATTR(THREAD_ATTR_USER);

void *fbp0;

int main(int argc, char **argv)
{
	int fps = 0;							// for calculating the frames per second
	char fpsDisplay[100];
	u32 tickResolution;
	u64 fpsTickNow;
	u64 fpsTickLast;

	void FPS(int&, char*, u32&, u64&, u64&);										// Display Frames Per Second 	
	initGraphics();

	pspDebugScreenInit();
	SetupCallbacks();

	sceRtcGetCurrentTick( &fpsTickLast );
	tickResolution = sceRtcGetTickResolution();
 
	while(1)
	{

		FPS(fps, fpsDisplay, tickResolution, fpsTickNow, fpsTickLast);
		flipScreen();
    }

	sceGuTerm();			// Terminating the Graphics System
	sceKernelExitGame();	// Quits Application
	return 0;
}

void mainMenu()
{
	
}

void FPS(int& fps, char* fpsDisplay[], u32& tickResolution, u64& fpsTickNow, u64& fpsTickLast)
{
	fps++;
	sceRtcGetCurrentTick( &fpsTickNow );
	
	if(((fpsTickNow - fpsTickLast) / ((float)tickResolution)) >= 1.0f)
	{
		fpsTickLast = fpsTickNow;
		sprintf( fpsDisplay, "FPS: %d", fps );
		fps = 0;
	}
	pspDebugScreenSetOffset( (int)fbp0 );
	pspDebugScreenSetXY( 0, 0 );
	pspDebugScreenPrintf( fpsDisplay );
 
}

Code in Graphics.h is optimised, contains a few extra functions and mostly uses the GU, but that doesn't seem to be the error, and i've used this code plently of times before....

[Archaemic]

You've got a forward declaration in the middle of a function. You can't do that. Move it above the main function.

[MiG]

You've got a forward declaration in the middle of a function. You can't do that. Move it above the main function.

I'm not with ya. Whats a forward declaration ?

[FreePlay]

You've got this in the middle of your main function:

void FPS(int&, char*, u32&, u64&, u64&);

Move it *outside* of the main function (above it).

[MiG]

You've got this in the middle of your main function:

void FPS(int&, char*, u32&, u64&, u64&);

Move it *outside* of the main function (above it).

why would that matter?

I'd got a program with around 10 Function Delcarations in the main() function..
I Don't get it... I was always told put function declarations before you use the function, not in global territory.

EDIT - I Moved it, same error..

[Archaemic]

Yes, before you use the function...but it has to be global.

[coolguy5678]

I need to know this. I have an array on the heap like this:

// (Throwable is a struct)
int numThrowables ;
Throwable* throwables ;
// ...
numThrowables = /* some value unknown at compile time */
throwables = malloc(sizeof(Throwable) * numThrowables) ;

How do I free this array? Will simply calling free(throwables) work or do I have to do something else?

[JaSo PsP]

im making a snake game, i can get a snake that is 5 blocks long to move around the screen using the directional buttons. Ive tried to make it add blocks to the snake but i cant seem to make it work correctly. Im not going to post the code, because its not the codr that is the problem. Here's what the situation is:

The snake starts like this: (H = head, b# = body part)

b4 b3 b2 b1 H

then when it moves the head moves forward and b4 goes to the old position of the head:

b3 b2 b1 b4 H

The body parts are an array of structures that hold the X and Y coords of themsleves. The snake length variable holds the length of the snake and during run time, each part of the snake is blitted to the screen according to the co-ordinates it hold. Now, heres where i ran into the problem. When i add a new part of the body, it has to insert it at the end of the array, meaning there is only one position that it will add the block instantly. For example: (F = Food)

b2 b1 b4 b3 H F  ->  b2 [b1b5] b4 b3 H

The new block overlaps the old one and the snake only appears longer when the snake is at is original state:

b5 b4 b3 b2 b1 H

So, there you have it, does anyone know the solution to this problem or have made a snake game themselves?

PS: if you really want to look at the code, here it is:

Spoiler for Code:

#include <pspdisplay.h>
#include <pspctrl.h>
#include <pspkernel.h>
#include <pspdebug.h>
#include <pspgu.h>
#include <png.h>
#include <stdio.h>
#include "graphics.h"

PSP_MODULE_INFO( "Snake", 0, 1, 1 );
typedef enum _bool { false, true } bool;

/* Exit callback */
int exit_callback(int arg1, int arg2, void *common) {
          sceKernelExitGame();
          return 0;
}

/* Callback thread */
int CallbackThread(SceSize args, void *argp) {
          int cbid;

          cbid = sceKernelCreateCallback("Exit Callback", exit_callback, NULL);
          sceKernelRegisterExitCallback(cbid);

          sceKernelSleepThreadCB();

          return 0;
}
/* Sets up the callback thread and returns its thread id */
int SetupCallbacks(void) {
          int thid = 0;

          thid = sceKernelCreateThread("update_thread", CallbackThread, 0x11, 0xFA0, 0, 0);
          if(thid >= 0) {
                    sceKernelStartThread(thid, 0, 0);
          }

          return thid;
}

typedef struct
{
        int x;
        int y;
} BodyPart;

void DrawBody();
void InitBody();

Image* Head;
Image* Back;
Image* Body;

BodyPart bodyParts[30];

enum{ DIR_UP, DIR_LEFT, DIR_RIGHT, DIR_DOWN };

int headX, headY, oldX, oldY;
int moveCount;
int dir;
int snakeLength, oldLength;
int i;
int back;

bool exitFlag;
bool newPart;

SceCtrlData pad;

int main()
{
    SetupCallbacks();
    initGraphics();
    
    headX = 80;
    headY = 80;
    
    moveCount = 0;
    
    snakeLength = 3;
    back = snakeLength;
    
    Head = loadImage( "body.png" );
    Back = loadImage( "back.png" );
    Body = Head;
    
    dir = DIR_RIGHT;
    
    exitFlag = false;
    newPart = false;
    
    InitBody();
    
    while( exitFlag == false )
    {
           clearScreen(0);
           sceCtrlReadBufferPositive(&pad, 1);
           
           blitAlphaImageToScreen( 0, 0, 480, 272, Back, 0, 0 );
           blitAlphaImageToScreen( 0, 0, 16, 16, Head, headX, headY );
           DrawBody();
           
           if( pad.Buttons & PSP_CTRL_UP )
               dir = DIR_UP;
           
           if( pad.Buttons & PSP_CTRL_DOWN )
               dir = DIR_DOWN;
           
           if( pad.Buttons & PSP_CTRL_LEFT )
               dir = DIR_LEFT;
           
           if( pad.Buttons & PSP_CTRL_RIGHT )
               dir = DIR_RIGHT;
           
           if( pad.Buttons & PSP_CTRL_START )
               exitFlag = true;
           
           if( moveCount >= 30 )
           {
               oldX = headX;
               oldY = headY;
               
               if( pad.Buttons & PSP_CTRL_CROSS )
               {
                    newPart = true;
               }
               
               switch( dir )
               {
                       case DIR_UP:
                            headY -= 16;
                            break;
                       
                       case DIR_DOWN:
                            headY += 16;
                            break;
                       
                       case DIR_LEFT:
                            headX -= 16;
                            break;
                       
                       case DIR_RIGHT:
                            headX += 16;
                            break;
                       
                       default:
                            break;
               }
               moveCount = 0;
               
               if( newPart == true )
               {
                   oldLength = snakeLength;
                   snakeLength++;
                   bodyParts[snakeLength].x = bodyParts[oldLength].x;
                   bodyParts[snakeLength].y = bodyParts[oldLength].y;
                   newPart = false;
               }
               
               bodyParts[back].x = oldX;
               bodyParts[back].y = oldY;
               if( back == 0 )
               {
                   back = snakeLength;
               }   
               else
               {
                   back--;
               }
           }
           
           flipScreen();
           moveCount++;
    }
    sceKernelExitGame();
    return 0;
}

void InitBody()
{
     bodyParts[0].x = 64;
     bodyParts[0].y = 80;
     
     bodyParts[1].x = 48;
     bodyParts[1].y = 80;
     
     bodyParts[2].x = 32;
     bodyParts[2].y = 80;
     
     bodyParts[3].x = 16;
     bodyParts[3].y = 80;
}

void DrawBody()
{
     for( i = 0; i < (snakeLength+1); i++ )
     {
          blitAlphaImageToScreen( 0, 0, 16, 16, Body, bodyParts[i].x, bodyParts[i].y );
     }
}

[MiG]

Yes, before you use the function...but it has to be global.

Well, I changed it, and same error. Function Declarations do not have to be global either.

[Archaemic]

I need to know this. I have an array on the heap like this:

// (throwable is a struct)
int numThrowables ;
Throwable* throwables ;
// ...
numThrowables = /* some value unknown at compile time */
throwables = malloc(sizeof(Throwable) * numThrowables) ;

How do I free this array? Will simply calling free(throwables) work or do I have to do something else?

free is how you do it. The size allocated with malloc is know to the free function.

[JaSo PsP]

I need to know this. I have an array on the heap like this:

// (Throwable is a struct)
int numThrowables ;
Throwable* throwables ;
// ...
numThrowables = /* some value unknown at compile time */
throwables = malloc(sizeof(Throwable) * numThrowables) ;

How do I free this array? Will simply calling free(throwables) work or do I have to do something else?

Yeah, im sure free() will work.

[Archaemic]

Well, I changed it, and same error. Function Declarations do not have to be global either.

Yeah, not in the case of private member functions. But that's only in C++.
AFAIK, in C, all functions are global scope.

[slicer4ever]

ok question why is atan2 messing up my other units?

ok here's whats hapeening:

Spoiler for code:

Spoiler for draw scene function:

void drawscene(void){
     for(int i=0;i<unit_num;i++){
          if(unit[i][3]==1){
               drone->x = unit[i][0];
               drone->y = unit[i][1];
               drone->angle = unit[i][2];
               if(selected_unit==i){
                    oslDrawRect(unit[i][0]-drone->sizeX/2,unit[i][1]-drone->sizeY/2,unit[i][0]+drone->sizeX/2,unit[i][1]+drone->sizeY/2,RGBA(0,255,0,255));
               }
               turrent_level_one->x = unit[i][0] + (int)oslSin((int)unit[i][2],23/2);
               turrent_level_one->y = unit[i][1] - (int)oslCos((int)unit[i][2],22/2);
               oslDrawImage(drone);
               oslDrawImage(turrent_level_one);
          }
          movement(i);
          if(osl_keys->pressed.cross){
               select_unit(i);
          }
     }
     if(selected_unit!=-1){
          if(osl_keys->pressed.circle){
              selected_unit=-1;
          }
     }
     if(osl_keys->pressed.triangle){
          build_drone();
     }
     cursor->x = cx;
     cursor->y = cy;
     oslDrawImage(cursor);
     cursorf();
}

Spoiler for movement function:

void movement(int check_unit){
     if(selected_unit != -1){
          if(osl_keys->pressed.cross){
               unit[selected_unit][4] = cx+mapx;
               unit[selected_unit][5] = cy+mapy;
               //unit[selected_unit][8] = atan2(unit[selected_unit][0]-unit[selected_unit][4],unit[selected_unit][1]-unit[selected_unit][5])*(180/PI)*-1;
          }
     }
     if((!(unit[check_unit][0]>unit[check_unit][4]-10 && unit[check_unit][0]<unit[check_unit][4]+10)) || (!(unit[check_unit][1]>unit[check_unit][5]-10 && unit[check_unit][1]<unit[check_unit][5]+10))){
          //unit[check_unit][8] = atan2(unit[check_unit][0]-unit[check_unit][4],unit[check_unit][1]-unit[check_unit][5])*(180/PI)*-1;
          if(unit[check_unit][2]>=unit[check_unit][8]){
               unit[check_unit][2]-=unit[check_unit][7];
          }else if(unit[check_unit][2]<unit[check_unit][8]){
               unit[check_unit][2]+=unit[check_unit][7];
          }
          unit[check_unit][0] += oslSin(unit[check_unit][2],unit[check_unit][6]);
          unit[check_unit][1] -= oslCos(unit[check_unit][2],unit[check_unit][6]);
     }
     oslSetTextColor(RGBA(0,0,255,255));
     oslSetBkColor(RGBA(0,0,0,0));
     oslPrintf_xy(0,10*check_unit,"x: %d",unit[check_unit][0]);
}

i determined it was the 2 atan2 commands which well screw up my units here's what i mean:

i select a unit any unit who hasen't been looped though well just jump to random locations on the screen and i don't know why

i hope i managed to get my problem across clearly and hope someone can help me

[JaSo PsP]

anyone wanna take a look at my problem on the previous page?

[MiG]

Yeah, not in the case of private member functions. But that's only in C++.
AFAIK, in C, all functions are global scope.

Right, ok. I've only really studied C++ so thought it was the same for C. I've now switched to C++ for the main file and now get the original error i was getting, the undefinded reference.. blah blah.

[Archaemic]

I checked, and the lines don't seem to match up with the errors they raise.

But you still can't do what you did in C++. I say private members, and that isn't a member at all, nor where you're defining it would ever be a member.

[MiG]

I checked, and the lines don't seem to match up with the errors they raise.

But you still can't do what you did in C++. I say private members, and that isn't a member at all, nor where you're defining it would ever be a member.

I've got a Full Pacman style game here written in C++ for the Console on the PC, and that compiles with function declerations just fine.

I'm pretty sure you can or surely my code wouldn't work ?

And I know, the errors just don't match up to the Code, it sucks.

[FreePlay]

I Don't get it... I was always told put function declarations before you use the function, not in global territory.

I'm pretty sure you can't use & in a function param... what are you trying to do, get the address of the argument? If so, you have to use * instead, and use & on the value you pass *into* the function so you're passing its address.

I've got a Full Pacman style game here written in C++ for the Console on the PC, and that compiles with function declerations just fine.

I'm pretty sure you can or surely my code wouldn't work ?

If you only ever use the locally-declared functions in the function where they're declared, it will probably work.

But declaring non-dynamically-located functions locally is generally a stupid idea... I have no idea who taught you to do that, but you should kick them hard in the shins.

[Archaemic]

Um, FreePlay, it's called passing by reference. Qt does it ALL THE TIME, so it must be valid.

[slicer4ever]

any1 for my prob?

[MiG]

I've got my project compiling now... I Have no idea why but i tried the extern thing again, and it worked :|

I swear it never worked before. :|

[slicer4ever]

hmmm...odd my prob just kinda disappeared i went back to my last setup and it still works fine i guess nvm now that it's working
-= Double Post =-
in the oslib what is the command to place a pixel i can only find the one's to draw lines,rectangles,and images

[Beat_Bob]

Can anyone help me?
(page 546)

[slicer4ever]

after a quick scan right here:
if(box.state==1 && box.jumpspeed==0)
{ box.y=box.y-0.8;
box.jumpspeed+=0.3;}
once the jumpspeed changes it doesn't again so it stays at that variable and a look into your code you probably want to change this to:

if(box.state==1 && box.jumpspeed<3.5)
{ box.y=box.y-0.8;
box.jumpspeed+=0.3;}

edit:
actually looking at it further you probably just want to drop the jumpstate and change it to:

if(box.state==1)
{ box.y=box.y-0.8;
box.jumpspeed+=0.3;}

ok after reading a little bit more this is what i think your fully after:

if(box.state==1 && box.jumpspeed<3.5)
{ box.y=box.y-0.8;
box.jumpspeed+=0.3;}

if (box.state==1 && box.jumpspeed>3.5)
{box.y=box.y-0.3;
//new line here to keep the jumpspeed increasing
box.jumpspeed+=0.3;}

if (box.state==1 && box.jumpspeed>=5);
{
box.state=2;
}

[FreePlay]

Um, FreePlay, it's called passing by reference. Qt does it ALL THE TIME, so it must be valid.

Yes. I realize that. I meant that in the function *declaration* I don't think it's possible to use & on one of your args, e.g. "void doSomething(char &x)". I know you can pass something by reference like this:

 int main()
 {
 	int a,b;
	a=5;
	b = 7;
	foo(&a, &b);
	printf("%d %d\n", a,b);
 }
 
 void foo(int *x, int *y)
 {
	*x = 6;
	*y = 8;
 }

and slicer, I already told him that.

[Raphael]

No, C++ really supports the ampersand as parameter modifier to mark it as "by reference" without making it a pointer (ie it's safer as it cannot be null and avoids all the pointer-pitfalls).
See f.e. http://www.tech-recipes.com/c_programming_tips1232.html

[FreePlay]

rrrrrreallly.

well, I do mostly C, anyways.

[Archaemic]

I'm fairly certain you can do it in C, too, but I'm not sure.

[yaustar]

I'm fairly certain you can do it in C, too, but I'm not sure.

No, you can only pass by pointer in C.

Edit: I stand corrected. I just tried this an you can pass by reference in C.