Game 4

Counting the Totals

Counting totals by eye doesn't scale. Meet the array — eleven counters in one named structure — and use the dice total itself as the index. One line tallies any roll, no chain of IFs. Twenty rolls in, the shape is still ragged.

Watching totals scroll past tells you they cluster, but to count them you’d need eleven separate variables — one for each total from 2 to 12 — and eleven IFs to decide which to add to. That’s the moment for a new tool: the array. One name, eleven slots, and the dice total picks the slot for you.

10 PRINT CHR$(147)
20 DIM T(12)
30 FOR I=1 TO 20
40 D=INT(RND(1)*6)+1+INT(RND(1)*6)+1
50 T(D)=T(D)+1
60 NEXT I
70 FOR F=2 TO 12
80 PRINT "TOTAL";F;"-";T(F)
90 NEXT F
A C64 screen listing tallies for totals 2 to 12 after 20 rolls: TOTAL 2 - 0, TOTAL 3 - 3, up to TOTAL 12 - 1, the counts uneven and lumpy.
Twenty rolls, tallied. The middle totals already lead, but with so few rolls the shape is ragged — some totals miss out entirely. The bell is hiding in too little data.

DIM T(12) on line 20 sets up the array: a row of counters numbered 0 to 12, all starting at zero. (You only use 2 to 12, and the spare low slots cost nothing.) The magic is line 50: T(D) = T(D)+1. The total D is used as the index — roll a 9 and T(9) goes up by one; roll a 7 and T(7) goes up. The value chooses its own counter. No IF, no testing — the number does the filing.

This is what arrays are for: many values under one name, reached by a number. After the loop, lines 70–90 walk F from 2 to 12 and print each count. But look at the figure — twenty rolls is too few. The middle leads, but the shape is lumpy and some totals are still empty. The pattern is there; it just needs more rolls to show itself.

Try this

  • Check the sum. Add up all eleven counts — they should come to exactly 20, the number of rolls. Every roll landed in exactly one slot.
  • One more total. The array runs to 12 because that’s the highest two dice can make. What would you change to tally three dice? (Hint: the top total, and the DIM.)

What’s next

Twenty rolls is too ragged to trust. In Unit 4 you roll a thousand — and the bell stops hiding and shows itself plainly in the numbers.