Game 4 Unit 3 of 6 1 hr learning time

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.

50% of Tally

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.