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.
Example 1-1. Initializing SDL
#include "SDL.h" /* All SDL App's need this */
+#include <stdio.h>
+
+int main(int argc, char *argv[]) {
+
+ 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);
+}