Beginning of the main function

Will start by explaining the main function, which begins in Listing 1.

Listing 1. Beginning of the main function. 
int main(){
  //NOTE THE USE OF LOCAL VARIABLES IN PLACE OF GLOBALS
  BITMAP* screenBuf = NULL;
  int xCoor = 0;
  int yCoor = 0;
  int color = 0;

  allegro_init();
  install_mouse();
  install_keyboard();
  set_color_depth(32);
  set_gfx_mode(GFX_AUTODETECT_WINDOWED,440,500,0,0);
  screenBuf = create_bitmap(440,500);
  show_mouse(screen);