© Glenn Rowe 20041 AC21001 - Lab 2 A simple card game (twenty- one)

© Glenn Rowe 2004 1

AC21001 - Lab 2A simple card game (twenty-one)


The game of 21 (blackjack) Computer versus human Use standard pack of cards Deal 2 cards to each player

one visible to both players the other hidden - visible only to one player

Aim: get a score as near 21 as possible without going over

Card values: Ace through 10 face value Jack, Queen or King worth 10 each


The game of 21 (rules)

Human has first turn decide whether to take one card or not if not, human stands on cards held (cannot take

any more cards on future turns) Computer turn is similar Play continues until either:

both players stand one player goes over 21 (goes bust)


Classes

Main classes: Card - a single card Pack - the pack of cards Player - computer or human TwentyOne - runs the game play


Card class

Card class represent one card in the pack 2 main properties:

rank (ace, 2, 3, …Jack, Queen, King) suit (spades, hearts, diamonds, clubs)

Rank can be int ace == 1, Jack == 11, Queen == 12, King == 13

Suit is string Provide interface methods & ToString method


Pack class Pack class

stores cards not yet used in play must allow variable size

Can use array of Cards e.g. Card **cards for a Java-type array in C++ or use one of other methods in C++

Methods: Initialize (set pack to full 52 cards) Shuffle DealCard


Pack class - Initialize method

Initialize card array - assign 52 cards to the array

00FE34D

cards

00FE457 00FE519 00FE623 […] […]

new Card*[52]

'cards' is a pointer to an arrayof pointers, so initialize it withcards = new Card*[52];




00FE34D

cards

00FE457 00FE519 00FE623 […] […]

new Card*[52]

Each pointer in the array mustthen be initialized to a newCard object.

E.g. for Ace of Spades:

cards[0] = new Card("Spade", 1);

[but use a loop for better efficiency!] Spade 1




00FE34D

cards

00FE457 00FE519 00FE623 […] […]

new Card*[52]

Can access a card's suit with codelike this:

string suit = card[0]->getSuit();

Spade 1


Pack class - dealing cards Need to deal cards in random order Two possibilities:

select a card at random from an ordered pack shuffle the pack and then deal cards in fixed order

If we select cards at random: need to mark a dealt card so it isn't selected again when most of pack is dealt, need to generate a lot

of random numbers to find undealt card Shuffling usually more efficient


Pack class - Shuffle method Various possibilities for shuffling algorithm Easiest is probably:

Pick 2 cards at random locations in the pack Swap them Repeat above steps several hundred times


Pack class - DealCard method If we have shuffled the pack: Maintain a 'topOfPack' marker in Pack class

records position of next card to be dealt To deal a card:

retrieve cards[topOfPack] then decrement topOfPack

Remember to test if topOfPack >= 0


Player class Represents computer or human player Requires:

1 array for visible cards Single Card variable for hidden card or could also use an array to allow for game variants AddCard() method

adds a card to either visible or hidden array CardsValue() method

calculates total value of all held cards ToString() for printing player's details


Player class - card array Use same method as in Pack class for array

of cards use Card **visible Allow array size that is large enough to hold a

reasonable selection of cards (say, 10) AddCard should add a Card to 'visible' array


Player class - CardsValue( ) CardsValue() totals up value of all cards held

(visible + hidden) Use interface methods from Card class to

retrieve card's rank Calculate value for each card and produce

sum


TwentyOne class TwentyOne class manages game play Will need:

One Pack object Two Player objects (one for human, one for

computer) In constructor:

initialize Pack and Players


TwentyOne class - game play To start game:

deal 2 cards to each player one hidden, one visible

For human's turn: Ask if they want a card If so, deal one (add to visible array) If not, mark human as 'standing' so they cannot

ask for any more cards on later turns


TwentyOne class - game play Computer's turn:

use your strategy to determine if computer takes a card e.g. if holding > 15, stand; otherwise take card or devise your own strategy

If computer takes card, add to visible list If not, mark computer as 'standing'


TwentyOne class - end of turn After each turn:

check total of cards held for player if player has gone bust (> 21), game is over if player has exactly 21, they win

After each pair of turns (human + computer): check if both players are 'standing' if so, game is over…calculate totals for both players player closest to 21 wins if scores equal, game is a draw


Destructors, copy constructors, = operators

For each class containing dynamic memory: write a destructor

Optionally: provide a copy constructor for each class and an overloaded = operator

Follow examples in lectures / notes Once you've done one, the rest should be

much the same


main( ) function main() should create a TwentyOne object Then offer user the option of playing as many

games as they like (use a loop as in nim lab)


Optional extras - double-valued ace In full rules, the ace can be worth either 1 or

11 Modify your program to allow this Creates possibility of a player being dealt a

'natural' 21 ace + 10-valued card


Optional extras - scoring / betting Keep score (how many wins, losses and

draws for each player) or… Introduce a simple betting system

e.g. each player bets a certain amount at each turn in the game

after each game, winner takes all or split the total amount 50/50 for a draw


Optional extras - computer strategy Do a bit of research on web Find out statistics for when it's best to take an

extra card and when to stand Incorporate these into your program

Documents

© Glenn Rowe 20041 AC21001 - Lab 2 A simple card game (twenty- one)