Beginning of the program

Program begins in Listing 1.

Listing 1. Beginning of the program named PutPixel02. 
#include <allegro.h>

int main(){
  allegro_init();//Allegro initialization
  install_keyboard();//Set up for keyboard input
  //Need to set the color depth before setting the
  // graphics mode.
  set_color_depth(32);
  //Set the graphics mode to a 256x256-pixel window.
  set_gfx_mode(GFX_AUTODETECT_WINDOWED,256,256,0,0);

The code in Listing 1 is essentially the same as the code that I explained in the previous and earlier lessons, so no further explanation of Figure 1 should be necessary.