Blackjack 2
1

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This worksheet is copyright © Richard Pawson 2025, and protected by the Creative Commons license: Attribution-NonCommercial-NoDerivatives 4.0 International. You may freely make and distribute copies of this worksheet as is, but if you modify this worksheet you may not distribute your modified version (outside your own teaching institution) without the author's permission. Please email the author to report errors or suggest improvements.

# Step 1: load the starting code

# a15f20d097542126cc9e83305716a364b9fb2c0c0fd30c28172424dfc2c14722 Elan 1.8.2 guest default_profile valid main let points be 1000 variable rounds set to 1 let game be new Game(points) call game.addPlayer(new AutomatedPlayer("Player A", strategyA, points)) call game.addPlayer(new AutomatedPlayer("Player B", strategyB, points)) while rounds > 0 call playOneRound(game) call clearKeyBuffer() call display(game) set rounds to rounds - 1 end while end main procedure playOneRound(game as Game) call game.newRound() call display(game) let dealer be game.dealer each player in game.players call player.startTurn() call display(game) while player.status is Status.active call player.nextAction(dealer.faceCard) call display(game) end while end each call dealer.play() call display(game) while dealer.status is Status.active call dealer.nextAction(dealer.faceCard) call display(game) end while call game.updatePoints() end procedure procedure display(game as Game) let html be "<style>{styleSheet}</style>{htmlForGame(game)}" call displayHtml(html) call pause(1500) end procedure function strategyA(p as Player, dealerFaceUp as Card) returns Action return Action.stand end function function strategyB(p as Player, dealerFaceUp as Card) returns Action return Action.draw end function [imported] procedure updatePoints(dealer as Dealer, player as Player, playerOutcome as Outcome) if playerOutcome is Outcome.winDouble then call player.changePointsBy(2) call dealer.changePointsBy(-2) else if playerOutcome is Outcome.win then call player.changePointsBy(1) call dealer.changePointsBy(-1) else if playerOutcome is Outcome.lose then call player.changePointsBy(-1) call dealer.changePointsBy(1) end if end procedure [imported] function determinePlayerOutcome(dealer as Dealer, player as Player) returns Outcome # These 'let' definitions are just to make the logic that follows them simpler to read let d be dealer.status let dTotal be dealer.handTotal let p be player.status let pTotal be player.handTotal let bust be Status.bust let bj be Status.blackjack let win be Outcome.win let winDouble be Outcome.winDouble let lose be Outcome.lose let draw be Outcome.draw variable playerOutcome set to draw if p is bust then set playerOutcome to lose else if (p is bj) and (d isnt bj) then set playerOutcome to winDouble else if d is bust then set playerOutcome to win else if (d is bj) and (p is bj) then set playerOutcome to draw else if p is bj then set playerOutcome to winDouble else if d is bj then set playerOutcome to lose else if pTotal > dTotal then set playerOutcome to win else if pTotal < dTotal then set playerOutcome to lose else # strictly, this 'else' clause is redundant - as the variable was initialised to 'draw' - but added for clarity set playerOutcome to draw end if return playerOutcome end function [imported] function dealCard(random as Float) returns Card let number be (random*52).floor() let rank be rankValue.keys()[(number/4).floor()] let suit be intAsSuit(number mod 4) return new Card(rank, suit) end function [imported] function intAsSuit(n as Int) returns Suit variable suit set to Suit.clubs if n is 1 then set suit to Suit.diamonds else if n is 2 then set suit to Suit.hearts else if n is 3 then set suit to Suit.spades end if return suit end function [imported] function htmlForGame(game as Game) returns String variable html set to "<div class='game'>" set html to html + htmlForPlayer(game.dealer) each player in game.players set html to html + htmlForPlayer(player) end each set html to html + "<div class='message'>{game.message}</div>" return html + "</div>" end function [imported] function htmlForPlayer(player as Player) returns String variable html set to "<div class='player'>" set html to html + "<div class='details'>{player.name} - {player.points} points {player.getMessage()}</div>" set html to html + "<div class='hand'>" each card in player.cards let suit be card.suit let rank be card.rank set html to html + htmlForCard(card) end each return html + "</div></div>" end function [imported] function htmlForCard(card as Card) returns String variable html set to "" if card.faceDown then set html to "<div class='card reversed'>" else let rank be card.rank let suit be card.suit let colour be colours[suit] let symbol be symbols[suit] set html to "<div class='card {colour}'>" let u be htmlForSpot("u", rank) let v be htmlForSpot("v", symbol) variable grid set to "" each location in gridByRank[rank] if location is "royal" then set grid to grid + htmlForSpot(location, rank) else set grid to grid + htmlForSpot(location, symbol) end if end each set html to html + "{u}{v}{grid}" end if return html + "</div>" end function [imported] function htmlForSpot(id as String, content as String) returns String return "<div class='{id}'>{content}</div>" end function [imported] class Game constructor(dealerStartPoints as Int) set property.dealer to new Dealer(dealerStartPoints) end constructor property dealer as Dealer property players as List<of Player> property message as String procedure newRound() call property.dealer.newHand() each player in property.players call player.newHand() end each end procedure procedure updatePoints() each player in property.players let playerOutcome be determinePlayerOutcome(property.dealer, player) call global.updatePoints(property.dealer, player, playerOutcome) end each end procedure procedure addPlayer(player as Player) call property.players.append(player) end procedure procedure setMessage(message as String) set property.message to message end procedure end class [imported] class Card constructor(rank as String, suit as Suit) set property.rank to rank set property.suit to suit set property.value to rankValue[rank] end constructor property suit as Suit property rank as String property value as Int property faceDown as Boolean procedure turnFaceUp() set property.faceDown to false end procedure procedure turnFaceDown() set property.faceDown to true end procedure end class [imported] abstract class Player property name as String property points as Int property cards as List<of Card> property handTotal as Int property hasSoftAce as Boolean property status as Status property hasTurn as Boolean procedure startTurn() if property.status is Status.active then set property.hasTurn to true end if end procedure procedure evaluateStatus(newCard as Card) if (cardCount() is 2) and (property.handTotal is 21) then set property.status to Status.blackjack else if (property.handTotal > 21) and (property.hasSoftAce) then set property.handTotal to property.handTotal - 10 set property.hasSoftAce to false else if property.handTotal > 21 then set property.status to Status.bust else if property.handTotal is 21 then set property.status to Status.standing end if if property.status isnt Status.active then set property.hasTurn to false end if end procedure procedure stand() set property.status to Status.standing set property.hasTurn to false end procedure procedure draw() let newCard be dealCard(random()) call property.cards.append(newCard) if newCard.rank is "A" then call addAce() else set property.handTotal to property.handTotal + newCard.value end if call evaluateStatus(newCard) end procedure procedure addAce() if property.hasSoftAce then set property.handTotal to property.handTotal + 1 else set property.handTotal to property.handTotal + 11 set property.hasSoftAce to true end if end procedure function cardCount() returns Int return property.cards.length() end function procedure changePointsBy(amount as Int) set property.points to property.points + amount end procedure abstract procedure newHand() procedure newHandHelper() set property.hasTurn to false set property.hasSoftAce to false set property.cards to empty List<of Card> set property.handTotal to 0 set property.status to Status.active call draw() call draw() end procedure abstract function getMessage() returns String function statusAsString() returns String variable msg set to "" let status be property.status if property.hasTurn then set msg to msg + " - PLAYING" else if status is Status.standing then set msg to msg + " - STANDING" else if status is Status.blackjack then set msg to msg + " - BLACKJACK" else if status is Status.bust then set msg to msg + " - BUST" end if return msg end function abstract procedure nextAction(dealerFaceCard as Card) end class [imported] class Dealer inherits Player constructor(startingPoints as Int) set property.name to "Dealer" set property.points to startingPoints end constructor property faceCard as Card property hasPlayed as Boolean procedure play() call startTurn() let hiddenCard be property.cards[1] call hiddenCard.turnFaceUp() set property.hasPlayed to true end procedure procedure newHand() set property.hasPlayed to false call newHandHelper() set property.faceCard to property.cards[0] let hiddenCard be property.cards[1] call hiddenCard.turnFaceDown() end procedure procedure nextAction(faceCard as Card) if property.handTotal < 17 then call draw() else call stand() end if end procedure function getMessage() returns String variable msg set to "" if property.hasPlayed then set msg to statusAsString() + " - hand total: {property.handTotal}" end if return msg end function end class [imported] class HumanPlayer inherits Player constructor(name as String, startingPoints as Int) set property.name to name set property.points to startingPoints end constructor procedure newHand() call newHandHelper() end procedure procedure nextAction(dealerFaceCard as Card) variable key set to "" call clearKeyBuffer() while key is "" set key to waitForKey() if key is "d" then call draw() else if key is "s" then call stand() else set key to "" end if end while end procedure function getMessage() returns String variable msg set to statusAsString() + "- hand total: {property.handTotal}" if property.hasTurn then set msg to msg + " - press 'd' to draw, 's' to stand" end if return msg end function end class [imported] class AutomatedPlayer inherits Player constructor(name as String, decisionFunc as Func<of Player, Card => Action>, startingPoints as Int) set property.name to name set property.decisionFunc to decisionFunc set property.points to startingPoints end constructor property decisionFunc as Func<of Player, Card => Action> procedure newHand() call newHandHelper() end procedure procedure nextAction(dealerFaceCard as Card) let act be decisionFunc(this, dealerFaceCard) if act is Action.draw then call draw() else call stand() end if end procedure function getMessage() returns String return statusAsString() + " - hand total: {property.handTotal}" end function end class [imported] enum Action stand, draw [imported] enum Outcome undecided, lose, draw, win, winDouble [imported] enum Status active, standing, blackjack, bust [imported] enum Suit clubs, diamonds, hearts, spades [imported] constant symbols set to {Suit.clubs:"&clubs;", Suit.diamonds:"&diams;", Suit.hearts:"&hearts;", Suit.spades:"&spades;"} [imported] constant rankValue set to {"2":2, "3":3, "4":4, "5":5, "6":6, "7":7, "8":8, "9":9, "10":10, "J":10, "Q":10, "K":10, "A":11} [imported] constant gridByRank set to {"A":{"royal"}, "2":{"b", "c"}, "3":{"a", "b", "c"}, "4":{"d", "e", "f", "g"}, "5":{"a", "d", "e", "f", "g"}, "6":{"d", "e", "f", "g", "h", "i"}, "7":{"d", "e", "f", "g", "h", "i", "l"}, "8":{"d", "e", "f", "g", "h", "i", "l", "m"}, "9":{"a", "d", "e", "f", "g", "n", "o", "p", "r"}, "10":{"d", "e", "f", "g", "n", "o", "p", "r", "s", "t"}, "J":{"royal"}, "Q":{"royal"}, "K":{"royal"}} [imported] constant colours set to {Suit.clubs:"black", Suit.diamonds:"red", Suit.hearts:"red", Suit.spades:"black"} [imported] constant styleSheet set to ':root {\n background-color: darkgreen;\n padding-left: 5px;\n}\n\n.game {\n padding: 5px;\n}\n\n.message, .details {\n color: white;\n font-family: Arial, Helvetica, sans-serif;\n}\n\n.hand {\n margin-top: 5px;\n height: 150px;\n padding-bottom: 10px;\n }\n \n.card {\n position: relative;\n float: left;\n background-color: white;\n width: 95px;\n height:140px;\n margin-right:10px;\n padding: 5px;\n border-radius: 5px;\n font-family: Helvetica, sans-serif; \n}\n.royal,.a,.b,.c,.d,.e,.f,.g,.h,.i,.j,.k,.l,.m,.n,.o,.p,.q,.r,.s,.t,.u,.v,.w,.x,.y,.z {position: absolute; text-align:center;}\n\n/* Standard spots */ \n .a,.b,.c,.d,.e,.f,.g,.h,.i,.l,.m,.n,.o,.p,.r,.s,.t {font-size: 30px;}\n\n /* columns */\n .d,.n,.h,.p,.f {left: 18px }\n .a,.b,.c,.l,.m,.s,.t {left: 43px;}\n .e,.o,.i,.r,.g {left: 68px}\n\n /* rows */\n .d,.b,.e {top: 0px}\n .s {top: 20px;}\n .l {top: 28px;}\n .n,.o {top: 37px;}\n .h,.a,.i {top: 57px}\n .p,.r {top: 75px;}\n .m {top: 86px;}\n .t {top: 93px;}\n .f,.c,.g {top: 114px;}\n\n/* royals */\n .royal {\n position: absolute;\n z-index: 1;\n width: 95px;\n height: 140px;\n line-height: 140px;\n font-size: 100px;\n }\n\n/* corner summary */\n .u {font-size: 15px; width: 15px; text-align: center; left: 0px; top: 2px;}\n .v {font-size: 20px; width: 15px; text-align: center; left: 0px; top: 12px;}\n\n/* suit colors */\n .red {color: red}\n .black {color: black}\n\n/* back */\n .card.reversed { background-color: rgba(0, 0, 255, 0.607);}'

Immediately file > auto save it to local file storage, so that changes you make are preserved.

Move onto the next step before running the program.

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# Step 2: exploring the code

Briefly describe the meaning of 'abstraction' in programming:

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# Step 3: automated players

Having run the program 3-4 times, which of the two players is operating the very 'high risk' strategy, and which the very 'cautious' strategy?

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# Step 4: identifying the better of the strategies

Having run the program to play 10 rounds automatically, how many points did the Dealer, and each of the players ended up with?

Run the program a second time, and record how many points ended up with this time

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# Step 5: speeding up the program

Make sure that you have ghosted the pause (instruction 31) and all five occurrences of call display procedureName?(game arguments?)0 within the playOneRound procedure. Then run the program. You will see that both of the two players have lost points - only the Dealer is ahead.

Which of the two players has lost the least points?

Given that the result is from playing 100 rounds, and each participant started with 1000 points, calculate the average points lost or gained per round expressed as a percentage, for the Dealer and each Player (where a loss is a negative percentage and a gain is positive). Show how you worked this out.

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# Step 6: the default strategies

What can you say that every function does?

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# Step 7:implement a simple strategy with a decision

With the changes, how many points does each have after running 100 games?

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# Step 8: simulating 10,000 rounds

After making the changes such that the display now only updated after the last round, approximately how long did it take to run 10,000 rounds of Blackjack?

How many points did the Dealer, and each Player end up with?

Given that Player B is mimicking the strategy of the Dealer, why are they still losing points to the Dealer? (If you can't see why, say so.)

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# Step 9: making use of the soft ace

After making the changes and running the new version, what were the points for Player A and Player B?

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# Step 10: paying attention to the Dealer's 'face up card'

After making the changes and running the new version, what were the points for Player A and Player B?

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# Step 11: expanding the scope of the previous rule

After making the changes and running the new version, what were the points for Player A and Player B?

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# Step 12: testing what you have learned

What does defining a named value as a 'variable' allow you to then do?

When defining a variable, what two things must you specify?

What kind of instruction is used to change the value of a variable?

What must the code written into the 'condition' field of an 'if' instruction evaluate to?

Some types offer 'properties'. What is a property?

If you have a named value and you want to see what properties (if any) you can access from it, how do you do that?

What happens if you try to compare two values that are of different types?

If an 'if instruction' is given an 'else' clause, under what condition is that else clause executed?

If you combine more than one operator within a condition, what must you be careful about?

And what is the best way to ensure that you don't run into a problem when combining operators?

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# Congratulations! You have finished this worksheet

Answers to the questions in the previous step:

- Q: What does defining a named value as a 'variable' allow you to then do? A: It allows you to change the value subsequently.
- When defining a variable, what two things must you specify? You must specify the name for the variable and its initial value.
- What kind of instruction is used to change the value of a variable? A: a set instruction.
- Q: What must the code written into the 'condition' field of an 'if' instruction evaluate to? A: It must evaluate to 'true' or 'false'
- Q: Some types offer 'properties'. What is a property? A: a piece of information
- Q: If you have a named value and you want to see what properties (if any) you can access from it, how do you do that? A: by typing a dot after the named value and selecting an option from the pop-up list
- Q: What happens if you try to compare two values that are of different types? A: You get a 'type incompatibility' error (like comparing apples and oranges)
- Q: If you combine more than one operator within a condition, what must you be careful about? A: operator precedence
- Q: And what is the best way to ensure that you don't run into a problem when combining operators? A: by using brackets to ensure that there is no ambiguity between which argument is applied to which operator.

If you are interested in taking this project further, watch this video first: