Copy the negated bitmap to the onscreen window

Listing 4 begins by copying the negated bitmap to the bottom of the onscreen window as shown in Figure 1.

Then Listing 4 blocks and waits for the user to press a key, at which time it destroys the memory bitmap and terminates the program.

Listing 4. Copy the negated bitmap to the onscreen window. 
  //Copy the modified bitmap to the onscreen window
  // immediately below the original image.
  blit(picA, screen, 0,0,0,330,324,330);

  //Block and wait until the user presses a key.
  readkey();
  
  //Destroy bitmaps to avoid memory leaks.
  destroy_bitmap(picA);

  return 0;//Return 0 to indicate a successful run.
}//end main function
END_OF_MAIN()