SDL Library Documentation
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# Initializing SDL

SDL is composed of eight subsystems - Audio, CDROM, Event Handling, File I/O, Joystick Handling, Threading, Timers and Video. Before you can use any of these subsystems they must be initialized by calling `SDL_Init` (or `SDL_InitSubSystem`. `SDL_Init` must be called before any other SDL function. It automatically initializes the Event Handling, File I/O and Threading subsystems and it takes a parameter specifying which other subsystems to initialize. So, to initialize the default subsystems and the Video subsystems you would call:

        SDL_Init ( SDL_INIT_VIDEO );

To initialize the default subsystems, the Video subsystem and the Timers subsystem you would call:

        SDL_Init ( SDL_INIT_VIDEO | SDL_INIT_TIMER );

`SDL_Init` is complemented by `SDL_Quit` (and `SDL_QuitSubSystem`). `SDL_Quit` shuts down all subsystems, including the default ones. It should always be called before a SDL application exits.

With `SDL_Init` and `SDL_Quit` firmly embedded in your programmers toolkit you can write your first and most basic SDL application. However, we must be prepare to handle errors. Many SDL functions return a value and indicates whether the function has succeeded or failed, `SDL_Init`, for instance, returns -1 if it could not initialize a subsystem. SDL provides a useful facility that allows you to determine exactly what the problem was, every time an error occurs within SDL an error message is stored which can be retrieved using `SDL_GetError`. Use this often, you can never know too much about an error.

    #include "SDL.h"   /* All SDL App's need this */
    #include <stdio.h>

    int main() {

        printf("Initializing SDL.\n");

        /* Initialize defaults, Video and Audio */
        if((SDL_Init(SDL_INIT_VIDEO|SDL_INIT_AUDIO)==-1)) {
            printf("Could not initialize SDL: %s.\n", SDL_GetError());
            exit(-1);
        }

        printf("SDL initialized.\n");

        printf("Quiting SDL.\n");

        /* Shutdown all subsystems */
        SDL_Quit();

        printf("Quiting....\n");

        exit(0);
    }

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