Small Basic > Small Basic E-Books > Basic Computer Games Small Basic Edition > Blackjack

This is a simulation of the card game of Blackjack or 21, Las Vegas style. This rather comprehensive version allows for up to seven players. On each hand each player may get another card (a hit), stand, split a hand in the event two identical cards were received, or double down. Also, the dealer will ask for an insurance bet if he has an exposed ace. Cards are automatically reshuffled as the 51st card is reached. For greater realism, you may wish to change this to the 41st card by changing the 51 to 41 in this code: If C<51 Then Goto LN230 EndIf   Actually, fanatical purists will want to modify the program so it uses three decks of cards instead of just one. This program originally surfaced at Digital Equipment Corp.; the author is unknown. Code Listing (Small Basic File: blackjck.sb):

This chapter is adapted from the book Basic Computer Games Small Basic Edition published by BibleByte Books. To purchase this book in its entirety, please see the Computer Science For Kids web site.

 
 
TextWindow.CursorLeft = 31
TextWindow.WriteLine("BLACKJACK")
TextWindow.CursorLeft = 15
TextWindow.WriteLine("CREATIVE COMPUTING  MORRISTOWN, NEW JERSEY")
TextWindow.WriteLine("")
TextWindow.WriteLine("")
TextWindow.WriteLine("")
Goto LN1500
Sub Sub100
'  --SUBROUTINE TO GET A CARD.  RESULT IS PUT IN X.
If (gs120) then
Goto ln120
endif

If C<51 Then
  Goto LN230
EndIf
ln120:
gs120 = "false"
TextWindow.WriteLine("RESHUFFLING")
For D=D To 1 Step -1
C=C-1
CArray[C]=DArray[D]
EndFor
For C1=52 To C Step -1
  C2=Math.GetRandomNumber(C1 - C + 1) + (C - 1)
C3=CArray[C2]
CArray[C2]=CArray[C1]
CArray[C1]=C3
EndFor
LN230:
X=CArray[C]
C=C+1
EndSub
Sub Sub300
'  --SUBROUTINE TO EVALUATE HAND I.  TOTAL IS PUT INTO
'  --QArray[I]. TOTALS HAVE THE FOLLOWING MEANING

'  --  2-10...HARD 2-10
'  -- 11-21...SOFT 11-21
'  -- 22-32...HARD 11-21
'  --  33+....BUSTED
Q=0
For Q2=1 To RArray[I]
X=PArray[I][Q2]
Sub500()
EndFor
QArray[I]=Q
EndSub
Sub Sub500
'  --SUBROUTINE TO ADD CARD X TO TOTAL Q.
X1=X
If X1>10 Then
  X1=10
EndIf
'    SAME AS X1=10 MIN X
Q1=Q+X1
If Q>=11 Then
  Goto LN590
EndIf
If X>1 Then
  Goto LN570
EndIf
Q=Q+11
Goto ln620
LN570:
Q=Q1
If (Q1>=11) then
Q = Q1 +11
endif
Goto ln620
LN590:
Q=Q1
If (Q<=21 AND Q1>21) then
Q = q1+1
endif
If Q<33 Then
  Goto LN620
EndIf
Q=-1
LN620:
EndSub
Sub Sub700
'CARD PRINTING SUBROUTINE)
'    D$ DEFINED ELSEWHERE
TextWindow.Write(Text.GetSubText(DD,3*X-2,3))
TextWindow.Write("  ")
EndSub
Sub Sub750
'ALTERNATIVE PRINTING ROUTINE)
TextWindow.Write(" "+Text.GetSubText(DD,3*X-1,2))
TextWindow.Write("   ")
EndSub
Sub Sub800
'  --SUBROUTINE TO PLAY OUT A HAND.
'  --NO SPLITTING OR BLACKJACKS ALLOWED
If gs860 then
Goto ln860
endif
If gs950 then
Goto ln950
endif
H1=5
LN830:
Sub1410()
H1=3
If (H = 1) Then
  Goto LN950
ElseIf (H = 2) Then
  Goto LN930
EndIf
ln860:
gs860 = "false"
Sub100()
BArray[I]=BArray[I]*2
TextWindow.WriteLine("RECEIVED A")
Sub700()
Sub1100()
If Q>0 Then
gs1300="true"
Sub1200()
EndIf
Goto ln1010
LN930:
gs1320 = "true"
Sub1200()
LN940:
Goto ln1010
ln950:
Sub100()
TextWindow.Write("RECEIVED A")
Sub700()
Sub1100()
If Q<0 Then
  Goto LN940
EndIf
TextWindow.Write("HIT? ")
Goto LN830
ln1010:
EndSub
Sub Sub1100
'  --SUBROUTINE TO ADD A CARD TO ROW I
RArray[I]=RArray[I]+1
PArray[I][RArray[I]]=X
Q=QArray[I]
Sub500()
QArray[I]=Q
If Q>=0 Then
  Goto LN1190
EndIf
TextWindow.WriteLine("...BUSTED")
Sub1200()
LN1190:
EndSub
Sub Sub1200
'  --SUBROUTINE TO DISCARD ROW I
If gs1300 then
Goto ln1300
endif
If gs1320 then
Goto ln1320
endif
LN1210:
If RArray[I]<>0 Then
  Goto LN1230
EndIf
Goto ln1330
LN1230:
D=D+1
DArray[D]=PArray[I][RArray[I]]
RArray[I]=RArray[I]-1
Goto LN1210
ln1300:
' PRINTS TOTAL OF HAND I ")
TextWindow.WriteLine("")
ln1320:
GS1320="FALSE"
AA=QArray[I]
Sub3400()
TextWindow.WriteLine("TOTAL IS "+AA)
ln1330:
EndSub
'  --SUBROUTINE TO READ REPLY
Sub Sub1410
'    I$ DEFINED ELSEWHERE
LN1420:
HD = TextWindow.Read()
HD=Text.GetSubText(HD, 1, 1)
For H=1 To H1 Step 2
If HD=Text.GetSubText(ID,H,1) Then
  Goto LN1480
EndIf
EndFor
TextWindow.Write("TYPE "+Text.GetSubText(ID,1,H1-1)+" OR "+Text.GetSubText(ID,H1,2)+" PLEASE ")
Goto LN1420
LN1480:
H=(H+1)/2
EndSub
LN1500:
'  --PROGRAM STARTS HERE
'  --INITIALIZE
DD="N A  2  3  4  5  6  7N 8  9 10  J  Q  K"
ID="H,S,D,/,"
For I=1 To 13
For J=4*I-3 To 4*I
DArray[J]=I
EndFor
EndFor
D=52
C=53
TextWindow.Write("DO YOU WANT INSTRUCTIONS? ")
HD = TextWindow.Read()
If Text.GetSubText(HD,1,1)="N" OR Text.GetSubText(HD,1,1)="n" Then
  Goto LN1760
EndIf
TextWindow.WriteLine("THIS IS THE GAME OF 21. AS MANY AS 7 PLAYERS MAY PLAY THE")
TextWindow.WriteLine("GAME. ON EACH DEAL, BETS WILL BE ASKED FOR, AND THE")
TextWindow.WriteLine("PLAYERS' BETS SHOULD BE TYPED IN. THE CARDS WILL THEN BE")
TextWindow.WriteLine("DEALT, AND EACH PLAYER IN TURN PLAYS HIS HAND. THE")
TextWindow.WriteLine("FIRST RESPONSE SHOULD BE EITHER 'D', INDICATING THAT THE")
TextWindow.WriteLine("PLAYER IS DOUBLING DOWN, 'S', INDICATING THAT HE IS")
TextWindow.WriteLine("STANDING, 'H', INDICATING HE WANTS ANOTHER CARD, OR '/',")
TextWindow.WriteLine("INDICATING THAT HE WANTS TO SPLIT HIS CARDS. AFTER THE")
TextWindow.WriteLine("INITIAL RESPONSE, ALL FURTHER RESPONSES SHOULD BE 'S' OR")
TextWindow.WriteLine("'H', UNLESS THE CARDS WERE SPLIT, IN WHICH CASE DOUBLING")
TextWindow.WriteLine("DOWN IS AGAIN PERMITTED. IN ORDER TO COLLECT FOR")
TextWindow.WriteLine("BLACKJACK, THE INITIAL RESPONSE SHOULD BE 'S'.")
LN1760:
TextWindow.Write("NUMBER OF PLAYERS? ")
N = TextWindow.ReadNumber()
TextWindow.WriteLine("")
If N<1 OR N>7 OR N>Math.Floor(N) Then
  Goto LN1760
EndIf
For I=1 To 8
TArray[I]=0
EndFor
D1=N+1
LN1810:
If 2*D1+C>=52 Then
'enter middle of sub
  GS120 = "true"
  Sub100()
EndIf
If C=2 Then
  C=C-1
EndIf
For I=1 To N
Z[I]=0
EndFor
For I=1 To 15
BArray[I]=0
EndFor
For I=1 To 15
QArray[I]=0
EndFor
For I=1 To 7
SArray[I]=0
EndFor
For I=1 To 15
RArray[I]=0
EndFor
LN1880:
TextWindow.WriteLine("BETS: ")
For I=1 To N
TextWindow.Write("#"+I+" ")
Z[I] = TextWindow.ReadNumber()
EndFor
For I=1 To N
If Z[I]<=0 OR Z[I]>500 Then
  Goto LN1880
EndIf
BArray[I]=Z[I]
EndFor
TextWindow.Write("PLAYER ")
For I=1 To N
TextWindow.Write(I + "     ")
EndFor
TextWindow.WriteLine("DEALER ")
For J=1 To 2
TextWindow.CursorLeft = 5
For I=1 To D1
Sub100()
PArray[I][J]=X
If J=1 OR I<=N Then
  Sub750()
EndIf
EndFor
TextWindow.WriteLine("")
EndFor
For I=1 To D1
RArray[I]=2
EndFor
'  --TEST FOR INSURANCE
If PArray[D1][1]>1 Then
  Goto LN2240
EndIf
TextWindow.Write("ANY INSURANCE? ")
HD= TextWindow.Read()
If text.GetSubText(HD,1,1)<>"Y" Then
  Goto LN2240
EndIf
LN2160:
TextWindow.WriteLine("INSURANCE BETS")
For I=1 To N
TextWindow.Write("#"+I+" ")
Z[I] = TextWindow.ReadNumber()
EndFor
For I=1 To N
If Z[I]<0 OR Z[I]>BArray[I]/2 Then
  Goto LN2160
EndIf
EndFor
For I=1 To N
  If PArray[D1][2]>=10 Then
    SArray[I]=Z[I]*(3*(-(-1))-1)
  Else
    SArray[I]=Z[I]*(3*(-(0))-1)
  EndIf
EndFor
LN2240:
'  --TEST FOR DEALER BLACKJACK
L1=1
L2=1
If PArray[D1][1]=1 AND PArray[D1][2]>9 Then
  L1=0
EndIf
L2=0
If PArray[D1][2]=1 AND PArray[D1][1]>9 Then
  L1=0
EndIf
L2=0
If L1<>0 OR L2<>0 Then
  Goto LN2320
EndIf
TextWindow.WriteLine("")
TextWindow.Write("DEALER HAS A"+Text.GetSubText(DD,3*PArray[D1][2]-2,3)+" IN THE HOLE ")
TextWindow.WriteLine("FOR BLACKJACK")
For I=1 To D1
Sub300()
EndFor
Goto LN3140
LN2320:
'  --NO DEALER BLACKJACK
If PArray[D1][1]>1 AND PArray[D1][1]<10 Then
  Goto LN2350
EndIf
TextWindow.WriteLine("")
TextWindow.WriteLine("NO DEALER BLACKJACK.")
LN2350:
'  --NOW PLAY THE HANDS
For I=1 To N
LN2370:
TextWindow.Write("PLAYER "+I+"? ")
H1=7
Sub1410()
If (H = 1) Then
  Goto LN2550
ElseIf (H = 2) Then
  Goto LN2410
ElseIf (H = 3) Then
  Goto LN2510
ElseIf (H = 4) Then
  Goto LN2600
EndIf
LN2410:
'  --PLAYER WANTS TO STAND
Sub300()
If QArray[I]<>21 Then
  Goto LN2490
EndIf
TextWindow.WriteLine("BLACKJACK")
SArray[I]=SArray[I]+1.5*BArray[I]
BArray[I]=0
Sub1200()
Goto LN2900
LN2490:
gs1320="true"
Sub1200()
Goto LN2900
LN2510:
'  --PLAYER WANTS TO DOUBLE DOWN
Sub300()
gs860 = "true"
Sub800()
Goto LN2900
LN2550:
'  --PLAYER WANTS TO BE HIT
Sub300()
H1=3
gs950="true"
Sub800()
Goto LN2900
LN2600:
'  --PLAYER WANTS TO SPLIT
L1=PArray[I][1]
If PArray[I][1]>10 Then
  L1=10
EndIf
L2=PArray[I][2]
If PArray[I][2]>10 Then
  L2=10
EndIf
If L1=L2 Then
  Goto LN2640
EndIf
TextWindow.WriteLine("SPLITTING NOT ALLOWED.")
Goto LN2370
LN2640:
'  --PLAY OUT SPLIT
I1=I+D1
RArray[I1]=2
PArray[I1][1]=PArray[I][2]
BArray[I+D1]=BArray[I]
Sub100()
TextWindow.Write("FIRST HAND RECEIVES A")
Sub700()
PArray[I][2]=X
Sub300()
TextWindow.WriteLine("")
Sub100()
TextWindow.Write("SECOND HAND RECEIVES A")
I=I1
Sub700()
PArray[I][2]=X
Sub300()
TextWindow.WriteLine("")
I=I1-D1
If PArray[I][1]=1 Then
  Goto LN2900
EndIf
'  --NOW PLAY THE TWO HANDS
LN2850:
If I > D1 Then
TextWindow.Write("HAND 2 ")
Else
TextWindow.Write("HAND 1 ")
EndIf

Sub800()
I=I+D1
If I=I1 Then
  Goto LN2850
EndIf
I=I1-D1
LN2900:
EndFor
Sub300()
'  --TEST FOR PLAYING DEALER'S HAND
For I=1 To N
If RArray[I]>0 OR RArray[I+D1]>0 Then
  Goto LN3010
EndIf
EndFor
TextWindow.Write("DEALER HAD A ")
X=PArray[D1][2]
Sub700()
TextWindow.WriteLine(" CONCEALED.")
Goto LN3140
LN3010:
TextWindow.Write("DEALER HAS A"+Text.GetSubText(DD,3*PArray[D1][2]-2,3)+" CONCEALED ")
I=D1
AA=QArray[I]
Sub3400()
TextWindow.WriteLine("FOR A TOTAL OF "+AA)
If AA>16 Then
  Goto LN3130
EndIf
TextWindow.Write("DRAWS")
LN3060:
Sub100()
Sub750()
Sub1100()
AA=Q
Sub3400()
If Q>0 AND AA<17 Then
  Goto LN3060
EndIf
If Q < 0 then
QArray[I]=Q-(-1)/2
else
QArray[I]=Q-(0)/2
endif

If Q<0 Then
  Goto LN3140
EndIf
AA=Q
Sub3400()
TextWindow.WriteLine("---TOTAL IS "+AA)
LN3130:
TextWindow.WriteLine("")
LN3140:
'  --TALLY THE RESULT

' 
ZD="LOSES PUSHES WINS "
TextWindow.WriteLine("")
For I=1 To N
AA=QArray[I]
Sub3400()
AB=QArray[I+D1]
Sub3410()
AC=QArray[D1]
Sub3420()
If AA > AC Then
  SArray[i] = SArray[i] + BArray[i]
ElseIf AA < AC then
  SArray[i] = SArray[i] - BArray[i]
EndIf
If AB > AC Then
  SArray[i] = SArray[i] +BArray[i+d1]
ElseIf AC < AB then
  SArray[i] = SArray[i] -BArray[i+d1]
EndIf

BArray[I+D1]=0
TextWindow.Write("PLAYER "+I+" ")
If SArray[i] > 0 Then
  TextWindow.Write(Text.GetSubText(ZD,(1)*6+7,6)+" ")
ElseIf SArray[i] =0 then
  TextWindow.Write(Text.GetSubText(ZD,(0)*6+7,6)+" ")
Else
  TextWindow.Write(Text.GetSubText(ZD,(-1)*6+7,6)+" ")
EndIf

If SArray[I]<>0 Then
  Goto LN3250
EndIf
TextWindow.Write("      ")
Goto LN3260
LN3250:
TextWindow.Write(Math.Abs(SArray[I]))
LN3260:
TArray[I]=TArray[I]+SArray[I]
TextWindow.WriteLine(" TOTAL= "+TArray[I])
Sub1200()
TArray[D1]=TArray[D1]-SArray[I]
I=I+D1
Sub1200()
I=I-D1
EndFor
TextWindow.WriteLine("DEALER'S TOTAL= "+TArray[D1])
TextWindow.WriteLine("")
Sub1200()
Goto LN1810
Sub Sub3400
  If (AA>=22) Then
    AA = AA - 11
  EndIf
EndSub
Sub Sub3410
  If (AB>=22) Then
    AB = AB - 11
  EndIf
EndSub
Sub Sub3420
  If (AC>=22) Then
    AC = AC - 11
  EndIf
EndSub

Sample Run:

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