Segmentation fault initializing SDL2. What am I doing wrong with memory? - c

Question

This is just suppose to display a bmp image to the SDL window front buffer. I played around with the code. And I think there is something wrong with my init() function. I'm new to SDL. But there must be a problem with my pointers or something I'm missing about SDL's fucntions
EDIT: I used GDB and it turned out my close() function was the problem. I believe it was because I was freeing memory that was set to NULL? I got rid of the close fucntion and just freed mem after my delay function.
#include <SDL2/SDL.h>
#include <stdio.h>
#include <stdbool.h>
#define SCREENWIDTH 640
#define SCREENHEIGHT 480
SDL_Window *win = NULL;
SDL_Surface *scrn = NULL;
SDL_Surface *mscrn = NULL;
bool init()
{
bool suc = true;
char name[11] = "Hello SDL";
if (SDL_Init(SDL_INIT_VIDEO) != 0) {
printf("%s", SDL_GetError());
suc = false;
}
win = SDL_CreateWindow(name, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREENWIDTH, SCREENHEIGHT, SDL_WINDOW_SHOWN);
if (win == NULL) {
printf("%s", SDL_GetError());
suc = false;
}
scrn = SDL_GetWindowSurface(win);
return suc;
}
bool loadmedia()
{
bool suc = true;
mscrn = SDL_LoadBMP("hello_world.bmp");
if (mscrn == NULL) {
printf("%s", SDL_GetError());
suc = false;
}
return suc;
}
void close()
{
SDL_FreeSurface(mscrn);
SDL_DestroyWindow(win);
SDL_Quit();
}
int main(int argc, char* args[])
{
if (!init()) {
close();
return 1;
}
if (!loadmedia()) {
close();
return 1;
}
SDL_BlitSurface(mscrn, NULL, scrn, NULL);
SDL_UpdateWindowSurface(win);
SDL_Delay(3000);
close();
return 0;
}

Answer 1

You should find a reasonable debugger and other tools to to find out which line is causing the error and why. Basically it boils down to using a debugger which usually comes with your IDE if you're using one, or using the very good code analysis tool, Valgrind.
If you're using gcc you can likely use gdb to debug your program easily. Here are some resources on how to help you diagnose segmentation faults:
Determine the line of C code that causes a segmentation fault?
http://www.cprogramming.com/debugging/segfaults.html
Get familiar with these tools, as they will save you countless hours in the future when you face new problems.