;Here you play TIC-TAC-TOE against›;the computer.  The computer plays›;by picking a random spot on the›;board.  If it is used, it picks›;another until it finds an unused›;place to play.›››MODULE››;use a global because the board is›;used by a number of different›;routines and each may or may not›;change it.  And we want that change›;to affect the board everywhere.›;›;The ARRAY goes from 1 to 9.  If that›;spot has a 0, that means it is unused.›;If it has a 1 that means the player›;has an X there.  A 2 means the computer›;placed a O there.››››BYTE ARRAY board(10)››››;This PROC draws the board with the›;X's and O's in their proper places,››PROC print_screen()››  BYTE i,›       j,›       k››  k=0›  PutE()›  FOR j=1 TO 3›  DO›    FOR i=1 TO 3›    DO›      k = k + 1›      IF board(k)=1 THEN›        Print("X")›      ELSEIF board(k)=2 THEN›        Print("O")›      ELSE›        Print(" ")›      FI›      IF i<>3 THEN›        Print("|")›      FI›    OD›    PutE()›    IF j<>3 THEN›      PrintE("")›    FI›  OD›RETURN›››;Here we clear out the board by putting›;0's in all the places››PROC clear_board()›  ›  BYTE i››  FOR i=1 TO 10›  DO›    board(i)=0›  OD›RETURN›››;Print a help screen so the player›;knows how to choose his position››PROC help()››  PutE()›  PrintE("The board is set up this:")›  PutE()›  PrintE("        1|2|3")›  PrintE("        ")›  PrintE("        4|5|6")›  PrintE("        ")›  PrintE("        7|8|9")›  PutE()›  PrintE("Enter 0 for help.")›  PutE()›RETURN›››;Here we check all the possible ways to›;win, vertical, horizontal and diagonal›;to see it the player has 3 1's in a row.›;It returns a 1 if the player has won›;and a 0 otherwise.››BYTE FUNC player_won()›  ›  BYTE rval›››  rval=0›  IF board(1)=1 AND board(2)=1 AND board(3)=1 THEN›    rval=1›  FI›  IF board(4)=1 AND board(5)=1 AND board(6)=1 THEN›    rval=1›  FI›  IF board(7)=1 AND board(8)=1 AND board(9)=1 THEN›    rval=1›  FI›  IF board(1)=1 AND board(4)=1 AND board(7)=1 THEN›    rval=1›  FI›  IF board(2)=1 AND board(5)=1 AND board(8)=1 THEN›    rval=1›  FI›  IF board(3)=1 AND board(6)=1 AND board(9)=1 THEN›    rval=1›  FI›  IF board(1)=1 AND board(5)=1 AND board(9)=1 THEN›    rval=1›  FI›  IF board(3)=1 AND board(5)=1 AND board(7)=1 THEN›    rval=1›  FI››RETURN(rval)›››;Same thing as the above except it sees›;if the computer has placed 3 2's in›;a row›››BYTE FUNC computer_won()›  ›  BYTE rval›››  rval=0›  IF board(1)=2 AND board(2)=2 AND board(3)=2 THEN›    rval=1›  FI›  IF board(4)=2 AND board(5)=2 AND board(6)=2 THEN›    rval=1›  FI›  IF board(7)=2 AND board(8)=2 AND board(9)=2 THEN›    rval=1›  FI›  IF board(1)=2 AND board(4)=2 AND board(7)=2 THEN›    rval=1›  FI›  IF board(2)=2 AND board(5)=2 AND board(8)=2 THEN›    rval=1›  FI›  IF board(3)=2 AND board(6)=2 AND board(9)=2 THEN›    rval=1›  FI›  IF board(1)=2 AND board(5)=2 AND board(9)=2 THEN›    rval=1›  FI›  IF board(3)=2 AND board(5)=2 AND board(7)=2 THEN›    rval=1›  FI››RETURN(rval)›››;Here the computer comes up with a›;random move.  If it is unused, it›;returns where it wants to move.  If›;it chooses a spot already taken, it›;picks until it finds a empty spot.›;After 30 tries, if it didn't find a›;empty spot, it just thinks the game is›;a tie ("Cat's game") and clears the›;board to start over››BYTE FUNC computer_turn()››  BYTE rnum,›       i››  i=0›  DO›    rnum=Rand(9)+1›    i = i + 1›    IF i>30 THEN›      PutE()›      PrintE("Cat's game.  We'll start over.")›      PutE()›      clear_board()›      EXIT›    FI›  UNTIL board(rnum)=0›  OD›RETURN(rnum)›››PROC main()››  CHAR ARRAY name(20)›  ›  BYTE move,›       winner››;* Set everything up *››  clear_board()›  Print("What is your name? ")›  InputS(name)›  PrintF("%EOk %S, you are X's.%E",name)›  help()›  winner=0››  DO›    print_screen()››;*Get the player's move*››    DO›      PrintF("%E%S's turn: ",name)›      move=InputB()›    UNTIL move<10›    OD› ›;*Do they need help?*››    IF move=0 THEN›      help()›      DO›        PrintF("%E%S's turn: ",name)›        move=InputB()›      UNTIL move<10›      OD›    FI››;*check to see if the spot is empty or not*››    IF board(move)<>0 THEN›      PrintE("That space is already taken!")›    ELSE›       board(move)=1›    FI›    print_screen()›   ›;*Did the player win?*››    IF player_won() THEN›      winner=1›      EXIT›    FI››;*Did the computer win? If not get it's move*››    IF computer_won() THEN›      winner=0›    ELSE›      move=computer_turn()›      board(move)=2›    FI›    PrintF("%EComputer's turn: %U%E",move)››  UNTIL computer_won()›  OD››;*If we get here, either the computer›; won or the player did (if the player›; won we EXIT out of the loop and the›; computer just used an UNTIL loop)*›››  print_screen()›  IF winner=1 THEN›    PrintF("%E%EYou Won!!!!!%E")›  ELSE›    PrintF("%E%ESorry, the computer beat you.%E")›  FI››RETURN››