154
The VIC 20
User
Guide
cards
on
the VIC
20.
This program fills a 52-element table D% with the
numbers I through
52
in a random sequence. (Element D% (0)
is
not used.)
The cards can be pegged to the random numbers in any way, such as
A=
1,2=
2,
3=
3,
...
,
Q=
12,
K=13
Spades
=0,
Hearts =
13,
Diamonds =
26,
Clubs =
42
With this scheme, the Ace of Spades = 1 + 0 =
1,
the Queen of
Spades
=
12
+ 0 =
12,
the Three
of
Hearts = 3 +
13
=
16,
and so on.
In the shuffle program, a 52-element flag table
FL
keeps track of
whether a card has been chosen.
PRINT
statements are inserted to display
the seed value, followed by the numbers, in a continuous-line format. Note
that exactly
52
numbers are displayed
and
that
no number
is
repeated. Each
program run will produce a new random sequence.
10
DIM
FL(~2),D~(52)
20
X=RND(-TI):PRINT
X
30
FOR
I-I
TO
52
40
:C~-52*RND(I)+1
50 :IF
FL(C~)<)e
OOTO
41
60 :
D:Y.(
n-c"
70
:PRINT
C:Y.;
80
NEXT
RUN
1. 18586613E-05
48
40
13
37
50
43
46
31
49 44
23
38
25
11
, 35 32 30
24
41
26
5 6 1
45
10
21
14
42
20
15
34
18
52
47
7
16
8
19
33
36
4
17
3
22
27 29
28
39
2
51
12
RUN
1.01154728E-06
14
35
52 50
26
48
27
36 34
25
18
20
41
33 39
7
46
24
23
28
1
9 3
12
43 2
31
44
4 1 32 37 3
o
40
22
45 48
42 49
16
11
6
10
2'
9
51
17
8
15
38
5
21
13
Notice that this program runs more slowly as it nears the 52nd number.
It
is
especially slow
on
the last card. This
is
because the program has to fetch
more and more random numbers to find one that has not already been
selected. A simple routine such as this has much room for improvement,
of
course. You can speed it up
just
by finding the last number in the program
from the table rather than waiting until it
is
selected randomly.
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