SDL (Simple DirectMedia Layer) - Getting started

In this section, we will show you how to initialise and shutdown SDL subsystems.

#include <stdio.h> /* printf and fprintf */

#ifdef _WIN32
#include <SDL/SDL.h> /* Windows-specific SDL2 library */
#else
#include <SDL2/SDL.h> /* macOS- and GNU/Linux-specific */
#endif
 
int main (int argc, char **argv)
{
  /*
  * Initialises the SDL video subsystem (as well as the events subsystem).
  * Returns 0 on success or a negative error code on failure using SDL_GetError().
  */
  if (SDL_Init(SDL_INIT_VIDEO) != 0)
  {
    fprintf(stderr, "SDL failed to initialise: %s\n", SDL_GetError());
    return 1;
  }
 	
  printf("SDL initialised!");

  /* Shuts down all SDL subsystems */
  SDL_Quit(); 
  
  return 0;
}

^{You can download the source code of this section in this GitLab repository. All source code is stored in this group.}

Linking SDL2 libraries

The basic functions required for SDL2 is either in the <SDL/SDL.h> library or <SDL2/SDL.h> library depending on the operating system, hence the above source code uses

#ifdef _WIN32
#include <SDL/SDL.h> /* Windows-specific SDL2 library */
#else
#include <SDL2/SDL.h> /* macOS- and GNU/Linux-specific */
#endif

main macro in Windows

When writing code for Windows machines, it is necessary to include

int main (int argc, char **argv)

since SDL overwrites the main macro. According to SDL's FAQWindows:

You should be using main() instead of WinMain() even though you are creating a Windows application, because SDL provides a version of WinMain() which performs some SDL initialization before calling your main code. If for some reason you need to use WinMain(), take a look at the SDL source code in src/main/win32/SDL_main.c to see what kind of initialization you need to do in your WinMain() function so that SDL works properly.

Initialising SDL subsystems

When using a SDL subsystem, you must always initialise it first. In the following if-statement, we initialise the SDL video subsystem with the flag SDL_INIT_VIDEO. If it succeeds, it returns 0, otherwise it returns a negative error code and will print information about the error using SDL_GetError through the stderr stream.

/*
* Initialises the SDL video subsystem (as well as the events subsystem).
* Returns 0 on success or a negative error code on failure using SDL_GetError().
*/
if (SDL_Init(SDL_INIT_VIDEO) != 0)
{
  fprintf(stderr, "SDL failed to initialise: %s\n", SDL_GetError());
  return 1;
}

You can initialise multiple subsystems using the | operator:

if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO) != 0)
{
  fprintf(stderr, "SDL failed to initialise: %s\n", SDL_GetError());
  return 1;
}

All information about the SDL_Init function subsystems, and their flags can be found in the SDL Wiki's SDL_Init page.

Shutting down SDL subsystems

To shut down the SDL subsystems, you must execute

SDL_Quit();

However, this will only shut down the main subsystems; shutting down the TTF subsystem requires a different function

TTF_Quit();