Segmentation fault while using SDL - c++

Question

[SOLVED]I'm following this tutorial (video) and I'm at this very moment. I had no problems with compiling, but when it comes to running the program it's just flashing for a second and turning off. So I've run the debugger and I found a segmentation fault from SDL_DisplayFormat in my load_image function, when I comment off lines where I load images it works ok, but I can't find the reason of the problem.
[SOLUTION] I haven't fill the .bmp files that is why the SDL_DisplayFormat didn't work. Once filed with drawning, everything started to work.
Here is my code:
#include "game.h"
/*TODO
*stworzyć plik z blokami "blocks.bmp"
*stworzyć plik z tlem "background.bmp"
*uzywac jako tla do obrazkow 000,255,255
*
*/
game::game()
{
//zaladowanie ekranu
SDL_Init(SDL_INIT_EVERYTHING);
screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGTH, 32, SDL_SWSURFACE);
//ladowanei obrazkow
//ustawianie polozenia i rozmiaru kamery
camera.x = camera.y = 0;
camera.w = SCREEN_WIDTH;
camera.h = SCREEN_HEIGTH;
//inicjalizacja kierunku w kotrym sie poruszamy
direction[0] = direction[1] = 0;
running = true;
block = (load_image("blocks.bmp"));
background = (load_image("background.bmp"));
}
game::~game()
{
SDL_FreeSurface(block);
SDL_FreeSurface(background);
SDL_Quit();
}
SDL_Surface* game::load_image (const char* filename)
{
SDL_Surface* tmp = SDL_LoadBMP(filename);
SDL_Surface* tmp2 = SDL_DisplayFormat(tmp);
//do odkomentowania kolorkey na razie zeby sprawdzac kolizje
// SDL_SetColorKey(tmp2, SDL_SRCCOLORKEY, SDL_MapRGB(screen->format, 0x00, 0xff, 0xff)
SDL_FreeSurface(tmp);
return tmp2;
}
void game::handleEvents()
{
SDL_Event event;
while(SDL_PollEvent(&event))
{
switch(event.type)
{
case SDL_QUIT:
running = false;
return;
case SDL_KEYDOWN:
switch(event.key.keysym.sym)
{
case SDLK_LEFT:
direction[0] = 1;
break;
case SDLK_RIGHT:
direction[1] = 1;
break;
}
break;
case SDL_KEYUP:
switch(event.key.keysym.sym)
{
case SDLK_LEFT:
direction[0] = 0;
break;
case SDLK_RIGHT:
direction[1] = 0;
break;
}
break;
}
}
}
void game::start()
{
while(1)
{
handleEvents();
SDL_Flip(screen);
}
}

Answer 1

One advise up front: Provide complete, minimal code including compile instructions. Yours doesn't have a main() function and the class definition is missing too (game.h). After reconstructing this and running it in a debugger, I find that the first SDL_LoadBMP() returns NULL (maybe that's the same at yours, but here it's definitely the case that I don't have the according files), so I have no clue if you have the same problem or not.
Now, what you can try to fix this is to check returnvalues. In this case, try this:
SDL_Surface* tmp = SDL_LoadBMP(filename);
if(!tmp)
throw std::runtime_error("SDL_LoadBMP() failed");
Using a unique_ptr or some custom wrapper class is also a good advice in order to not leak resources.