'===========================================================================
' Subject: CARD SHUFFLE                      Date: 06-29-96 (20:16)       
' Author:  Jonathan Leger                    Code: QB, QBasic, PDS        
' Origin:  leger@mail.dtx.net              Packet: DEMOS.ABC
'===========================================================================
DEFINT A-Z

DECLARE SUB MakeDeck (deck$)
DECLARE SUB Shuffle (deck$)

DECLARE FUNCTION CardValue (card$)
DECLARE FUNCTION DrawCard$ (deck$)
DECLARE FUNCTION DealCards$ (deck$, numcards)

CONST TRUE = -1
CONST FALSE = NOT TRUE

CLS

MakeDeck newdeck$          '*** Build a deck
Shuffle newdeck$           '*** Shuffle the deck

FUNCTION CardValue (card$)

'*** Returns the value of a card.  This should be changed depending on the
'*** particular game you are playing.

SELECT CASE LEFT$(card$, 1)
       CASE "A"                  '*** Aces are worth 15
            CardValue = 15
       CASE "K", "Q", "J", "0"   '*** Face cards and 10 are worth 10
            CardValue = 10
       CASE ELSE                 '*** All other cards are worth their
                                 '*** numerical value (2C=2, 3C=3, etc.)
            CardValue = VAL(LEFT$(card$, 1))
END SELECT

END FUNCTION

FUNCTION DealCards$ (deck$, numcards)

'*** Returns the next numcards cards in the deck and cuts those cards
'*** out of the deck.  This function should be used when a player draws
'*** a card (or cards) as well as when dealing.

Deal$ = LEFT$(deck$, numcards * 2)
deck$ = RIGHT$(deck$, LEN(deck$) - numcards * 2)

END FUNCTION

DEFSNG A-Z
SUB MakeDeck (deck$)

'*** Simply stuffs all of the cards in a deck into a string, deck$
deck$ = "2H3H4H5H6H7H8H9H0HJHQHKHAH"
deck$ = deck$ + "2S3S4S5S6S7S8S9S0SJSQSKSAS"
deck$ = deck$ + "2D3D4D5D6D7D8D9D0DJDQDKDAD"
deck$ = deck$ + "2C3C4C5C6C7C8C9C0CJCQCKCAC"

END SUB

SUB Shuffle (deck$)

'*** Copy the deck into a temporary deck so we can mess with the deck.
tempdeck$ = deck$

'*** It's good not to have the same deck every time we shuffle, so we
'*** generate a random number seed from the CPU's timer.
RANDOMIZE TIMER

'*** Let's shuffle it!
FOR card = 52 TO 1 STEP -1
  
   '*** Chose which card will be the next card "shuffled" into the deck.
   nextcard = INT(RND * card) + 1

   '*** Get the location of that card in the temporary deck.
   cardloc = ((nextcard - 1) * 2) + 1

   '*** Extract the card from the temporary deck.
   nextcard$ = MID$(tempdeck$, cardloc, 2)

   '*** Add the new card to the "shuffled" deck.
   newdeck$ = newdeck$ + nextcard$

   '*** Remove the new card from the temporary deck.
   tempdeck$ = LEFT$(tempdeck$, cardloc - 1) + RIGHT$(tempdeck$, LEN(tempdeck$) - cardloc - 1)

NEXT card

'*** Copy the new "shuffled" deck into the deck variable passed to the sub.
deck$ = newdeck$

END SUB