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  56 >Chapter 1. The Basics</TD
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  78 >Initializing SDL</H1
  79 ><P
  80 >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 <A
  81 HREF="sdlinit.html"
  82 ><TT
  83 CLASS="FUNCTION"
  84 >SDL_Init</TT
  85 ></A
  86 > (or <A
  87 HREF="sdlinitsubsystem.html"
  88 ><TT
  89 CLASS="FUNCTION"
  90 >SDL_InitSubSystem</TT
  91 ></A
  92 >). <TT
  93 CLASS="FUNCTION"
  94 >SDL_Init</TT
  95 > 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:
  96 <PRE
  97 CLASS="PROGRAMLISTING"
  98 >    SDL_Init ( SDL_INIT_VIDEO );</PRE
  99 >
 100 To initialize the default subsystems, the Video subsystem and the Timers subsystem you would call:
 101 <PRE
 102 CLASS="PROGRAMLISTING"
 103 >    SDL_Init ( SDL_INIT_VIDEO | SDL_INIT_TIMER );</PRE
 104 ></P
 105 ><P
 106 ><TT
 107 CLASS="FUNCTION"
 108 >SDL_Init</TT
 109 > is complemented by <A
 110 HREF="sdlquit.html"
 111 ><TT
 112 CLASS="FUNCTION"
 113 >SDL_Quit</TT
 114 ></A
 115 > (and <A
 116 HREF="sdlquitsubsystem.html"
 117 ><TT
 118 CLASS="FUNCTION"
 119 >SDL_QuitSubSystem</TT
 120 ></A
 121 >). <TT
 122 CLASS="FUNCTION"
 123 >SDL_Quit</TT
 124 > shuts down all subsystems, including the default ones. It should always be called before a SDL application exits.</P
 125 ><P
 126 >With <TT
 127 CLASS="FUNCTION"
 128 >SDL_Init</TT
 129 > and <TT
 130 CLASS="FUNCTION"
 131 >SDL_Quit</TT
 132 > 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, <TT
 133 CLASS="FUNCTION"
 134 >SDL_Init</TT
 135 >, 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 <TT
 136 CLASS="FUNCTION"
 137 >SDL_GetError</TT
 138 >. Use this often, you can never know too much about an error.</P
 139 ><DIV
 140 CLASS="EXAMPLE"
 141 ><A
 142 NAME="AEN60"
 143 ></A
 144 ><P
 145 ><B
 146 >Example 1-1. Initializing SDL</B
 147 ></P
 148 ><PRE
 149 CLASS="PROGRAMLISTING"
 150 >#include "SDL.h"   /* All SDL App's need this */
 151 #include &#60;stdio.h&#62;
 152
 153 int main(int argc, char *argv[]) {
 154
 155     printf("Initializing SDL.\n");
 156
 157     /* Initialize defaults, Video and Audio */
 158     if((SDL_Init(SDL_INIT_VIDEO|SDL_INIT_AUDIO)==-1)) {
 159         printf("Could not initialize SDL: %s.\n", SDL_GetError());
 160         exit(-1);
 161     }
 162
 163     printf("SDL initialized.\n");
 164
 165     printf("Quiting SDL.\n");
 166
 167     /* Shutdown all subsystems */
 168     SDL_Quit();
 169
 170     printf("Quiting....\n");
 171
 172     exit(0);
 173 }&#13;</PRE
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