Segmentation error from variable to string?!?

[YamiZee]

I have an odd problem... My code down there is me just testing sdl stuff... but my problem is in the code...

When i compile this code, it gives me "Segmentation fault (core dumped)"! Now if i comment out line 76, it works again! Now if i uncomment lines 75 and 78, it gives the error again! What I dont understand is why just adding those lines of codes, makes the whole thing not work?!?

All I wanted to do is turn my variables to strings so i can use them with ttf...
So any ideas???

#include <SDL/SDL.h>
#include <SDL/SDL_ttf.h>
#include <SDL/SDL_mixer.h>
#include <cmath>
#include <iostream>
#include <sstream>
#include <string> 
#include <boost/lexical_cast.hpp>
//#include "class1.h"
//g++ main.cpp -lSDL -lSDL_ttf -lSDL_mixer
//Sprite Color Border Object Kollision Location

//using namespace std;

//FUNCTIONS



int rectCollision(SDL_Rect* rect1,SDL_Rect* rect2){
  if		 (rect1->x+rect1->w < rect2->x)         return 0;
  else if(rect1->x          > rect2->x+rect2->w)return 0;
  else if(rect1->y+rect1->h < rect2->y)         return 0;
  else if(rect1->y          > rect2->y+rect2->h)return 0;
	int colL=abs(rect1->x+rect1->w - rect2->x);
	int colR=abs(rect1->x          - rect2->x+rect2->w);
	int colU=abs(rect1->y+rect1->h - rect2->y);
	int colD=abs(rect1->y          - rect2->y+rect2->h);
	if(colL<=colR&&colL<=colU&&colL<=colD)return 1;
	else if				(colR<=colU&&colR<=colD)return 2;
	else if										(colU<=colD)return 3;
	else																	return 4;
}

int getIndex(int col, int row, int ncol){ return row*ncol+col;}

void setBorder(SDL_Rect* clip,int x1,int y1,int x2,int y2){
  int w=x2/x1;
  int h=y2/y1;
  for(int i=0; i<x1; i++){
    for(int j=0; j<y1; j++){
      clip[getIndex(i,j,x1)].x=w*i;
      clip[getIndex(i,j,x1)].y=h*j;
      clip[getIndex(i,j,x1)].w=w;//w*(i+1)-1;
      clip[getIndex(i,j,x1)].h=h;//h*(i+1)-1;
      //clip[i][j].x=w*i;
      //clip[i][j].y=h*j;
      //clip[i][j].w=w;//w*(i+1)-1;
      //clip[i][j].h=h;//h*(i+1)-1;
    } 
  }
}



//MAIN SCOPE


//int main(){
int main(int argc,char** argv){ 
//int main(int argc, char* args[]){

  //SDL INIT
	SDL_Init(SDL_INIT_EVERYTHING);
	SDL_Surface* screen,*text,*icon,*image,*obj2S;
	screen=SDL_SetVideoMode(640,480,32,SDL_SWSURFACE); 
					   //SDL_DOUBLEBUF
					   //SDL_D...|FULLSCREEN
	SDL_WM_SetIcon(icon,NULL);
	SDL_WM_SetCaption("Hello World!",NULL);

  //SDL_TTF INIT
  TTF_Init();//Init ttf
  TTF_Font* fontDef=TTF_OpenFont("setbackt.ttf",100);//make font
  SDL_Color fontC={0,0,0};//font color
	//int foo=5;
	std::stringstream fontTxt;
	//fontTxt<<"foo is " << foo;
	//std::string fontTxt="foo is "+boost::lexical_cast<std::string>(foo);
	//char fontTxt[10];
	//sprintf(fontTxt,"%d",foo);
  text=TTF_RenderText_Solid(fontDef,"hi",fontC);//set font
  SDL_Rect fontL;//fonts location
  fontL.x=170;
  fontL.y=170;

	

	//SDL_MIXER INIT
	Mix_Chunk* effect1;
	Mix_Music* music1;
	Mix_OpenAudio(22050,MIX_DEFAULT_FORMAT,2,4096);
	music1=Mix_LoadMUS("music1.wav");
	effect1=Mix_LoadWAV("effect1.wav");
	

  //FPS
	Uint32 start;
	Uint32 start2;
	const int FPS=30;
	int FPS2;
	int FPS3;
	int FPScounter=FPS;
	int FPSsel=1;
  
  //KEY VARIABLES
	bool keyMouseL=0;
	bool keyMouseR=0;
  bool keyLeft=0;
  bool keyRight=0;
  bool keyUp=0;
  bool keyDown=0;

	//MISC VARIABLES
	SDL_Rect mouseXY;
	mouseXY.w=70;
	mouseXY.h=17;
  Uint32 rectC=SDL_MapRGB(screen->format,0xff,0x00,0x00);
  Uint32 bgC=SDL_MapRGB(screen->format,0xaa,0xaa,0xff);

  //OBJ2 DATA
  SDL_Rect obj2XY;//Location
  obj2XY.x=170;
  obj2XY.y=170;
  int obj2AX=11;//Sprite X and Y
  int obj2AY=1;
  SDL_Rect obj2B[obj2AX*obj2AY];//[obj2AX][obj2AY];//Border
  setBorder(obj2B,obj2AX,obj2AY,932,68);
  int obj2Spd=10;//Movement Speed
  int obj2FX=-1;//Frame
  int obj2FY=0;
  obj2S=SDL_DisplayFormat(SDL_LoadBMP("low.bmp"));//image
  SDL_SetColorKey(obj2S,SDL_SRCCOLORKEY,SDL_MapRGB(screen->format,0x00,0xff,0xff));//transparency

  //LOADING IMAGE
  image=SDL_DisplayFormat(SDL_LoadBMP("bmp.bmp"));
  SDL_SetColorKey(image,SDL_SRCCOLORKEY,SDL_MapRGB(screen->format,0x00,0xff,0x00));

//GAME LOOP
	bool running = true;
	while(running){
		start=SDL_GetTicks();
	


//INPUT



  //INPUT INIT
		SDL_Event event;
		while(SDL_PollEvent(&event)){
			switch(event.type){
				case SDL_QUIT:
					running=false;
					break;

	//MOUSE MOTION
				case SDL_MOUSEMOTION:
					mouseXY.x= event.motion.x;
					mouseXY.y= event.motion.y;
					break;

	//MOUSE DOWN
				case SDL_MOUSEBUTTONDOWN:
					switch(event.button.button){
						case SDL_BUTTON_LEFT:
							keyMouseL=1;
							break;
						case SDL_BUTTON_RIGHT:
							keyMouseR=1;
							break;
					}
					mouseXY.x= event.motion.x;
					mouseXY.y= event.motion.y;
					break;

	//MOUSE UP
				case SDL_MOUSEBUTTONUP:
					switch(event.button.button){
						case SDL_BUTTON_LEFT:
							keyMouseL=0;
							break;
						case SDL_BUTTON_RIGHT:
							keyMouseR=0;
							break;
					}
					mouseXY.x= event.motion.x;
					mouseXY.y= event.motion.y;
					break;
					

  //KEYDOWN
        case SDL_KEYDOWN:
          switch(event.key.keysym.sym){
            case SDLK_ESCAPE:
              SDL_Quit();
            case SDLK_LEFT:
              keyLeft=1;
              break;
            case SDLK_RIGHT:
              keyRight=1;
              break;
            case SDLK_UP:
              keyUp=1;
              break;
            case SDLK_DOWN:
              keyDown=1;
              break;}
          break;

  //KEYUP
        case SDL_KEYUP:
          switch(event.key.keysym.sym){
            case SDLK_LEFT:
              keyLeft=0;
              break;
            case SDLK_RIGHT:
              keyRight=0;
              break;
            case SDLK_UP:
              keyUp=0;
              break;
            case SDLK_DOWN:
              keyDown=0;
              break;
            case SDLK_1:
              Mix_PlayMusic(music1,0);
              break;
            case SDLK_2:
              Mix_PlayChannel(-1,effect1,0);//ch,effect,reps
              break;
            case SDLK_3:
              
              break;
            case SDLK_4:
              
              break;}
			}//s event.type
		}//w polling



//LOGIC



  //KEY LOGIC
    if(keyLeft){  obj2XY.x-=obj2Spd;}
    if(keyRight){ obj2XY.x+=obj2Spd;}
    if(keyUp){    obj2XY.y-=obj2Spd;}
    if(keyDown){  obj2XY.y+=obj2Spd;}

  //FRAME LOGIC
    /*if(obj2FX<obj2AX){
      obj2FX++;
    }else if(obj2FY<obj2AY){
      obj2FY++;
      obj2FX=0;
    }else{
      obj2FY=0;
      obj2FX=0;
    }*/
    if(obj2FX<obj2AX*obj2AY-1)
      obj2FX++;
    else 
      obj2FX=0;



//OUTPUT



    SDL_FillRect(screen,&screen->clip_rect,bgC);//BG color is bgC
		SDL_FillRect(screen,&mouseXY,rectC);//rectangle/mouse

      //image,border,screen,location
    SDL_BlitSurface(image,NULL,screen,NULL);//image
    SDL_BlitSurface(obj2S,&obj2B[obj2FX],screen,&obj2XY);//obj2
    SDL_BlitSurface(text,NULL,screen,&fontL);//text
 

    SDL_Flip(screen);

	//FPS STUFF
		if(1000/FPS>SDL_GetTicks()-start)
			SDL_Delay(1000/FPS-(SDL_GetTicks()-start));
		FPS2 = (1000/(SDL_GetTicks()-start));
		if(FPScounter>=FPS-1){
			FPS3=SDL_GetTicks()-start2;
			start2=SDL_GetTicks();
			FPScounter=0;
		  if(FPSsel==1){FPSsel=0;}else{}
		}else{
			FPScounter+=1;}
	//running=false;

	}//w running



//QUIT PROGRAM



  SDL_FreeSurface(image);
  SDL_FreeSurface(text);
	Mix_FreeChunk(effect1);
	Mix_FreeMusic(music1);
	Mix_CloseAudio();
  TTF_CloseFont(fontDef);
  TTF_Quit();
	SDL_Quit();
	return 0;
}

[zb0S216C]

YamiZee wrote:

"My code down there is me just testing sdl stuff..."

Right...

YamiZee wrote:

"but my problem is in the code..."

The code wasn't my first guess, but thanks for pointing that out.

YamiZee wrote:

"Now if i uncomment lines 75 and 78, it gives the error again!"

Compilation errors, or a segmentation fault error?

_Wazzak

[YamiZee]

lol your comments... anyway, like i said, it compiles just fine, but when i try to run it, it gives "Segmentation fault (core dumped)"...

[zb0S216C]

Segmentation faults are caused by attempting to read memory that's beyond your program's address space. These sorts of errors can be avoided by passing by reference (preferred), or by checking for null pointers.

What does fontTxt do, exactly (what's its purpose in the code)?

_Wazzak

[YamiZee]

At the moment, nothing! The only line it occurs in is the one where i declare it as a stringstream type (76). So all i do is declare it, and then comes the error just like that?!?

[zb0S216C]

Unused variables/objects are omitted before the code is compiled. Since fontTxt is unused, it'll be removed. However, since it's causing a run-time error, it could only mean it's still there, and something is attempting to read from it while it's in an invalid state. Try cleaning your project, and rebuilding.

_Wazzak

[YamiZee]

Actually i havent written anything to access it... all lines which contain it are commented out... even try Ctrl+F it! Also i figured out something new... when i comment out that line (76), and uncomment just the variable declaration for int foo (75), it again gives the error, even though im only creating a variable?!? ...maybe theres some problem with memory or something... I really have no idea!

[zb0S216C]

What error do you get if you uncomment int foo?

_Wazzak

[YamiZee]

The same... "Segmentation fault (core dumped)".....

[zb0S216C]

Hmmm... Try initialising these to null:

SDL_Surface* screen,*text,*icon,*image,*obj2S;

_Wazzak

[YamiZee]

Hmm... after i commented out line 68, it stopped giving errors of the other lines... however it may only be temporary... it may come back after declaring more variables or something... I find this particular case, quite unpredictable, so i have no idea what will happen from now... i wasnt exactly using line 68, i only declared it without using it...

Anyway, based on what ive seen so far, the error will come back if i continue adding variables... btw i stumbled upon this, attempting to get rid of the surfaces like you said... ill continue to work on my project, and if the error pops up again, ill come back...

Anyway, do you have any idea why all this was happening?

[zb0S216C]

YamiZee wrote:

"Anyway, do you have any idea why all this was happening?"

No, and the fact that a basic integer variable causes a segmentation fault is baffling. Have you considered redesigning your program?

Here's what I recommend you do:

1) Pass by reference. A reference will always refer to another object, and never calls for a null-check.
2) Check for null pointers. Pointers, unlike references, can be null. Attempts to access a null-pointer can cause run-time errors, such as segmentation faults.

3) Check for function failure. If a function fails, it will either throw an exception (run-time error), or will return a return-code. Check the SDL documentation to see if any functions you're calling are throwing exceptions, and see what they return.

4) Break your code down some more. Your main() is cluttered. Break it down into separate functions - you'll thank yourself later.

_Wazzak

[Peter87]

Make sure font is loaded correctly? If TTF_OpenFont can't find the file (setbackt.ttf) it will return a null pointer.