After the Christmas break, I was to teach my class the basics of the C language. Now this was more like it; I had spent the previous three years as a full-time C programmer so I was very comfortable with the language. However, in the first class of the New Year I made my first mistake.
I announced that we were going to teach a computer how to play Poker. I thought this might generate some excitement; instead, I got a number of puzzled looks. No one said anything, so I began by explaining that we first had to break the program down into discrete data and procedures. The logical place to start was to define what a deck of cards is to the computer. So, I wrote the playing card sequence on the board in four columns, each column headed by an initial to indicate the suit. Already I sensed that I had lost some of the class.
A group of women wearing dark clothing were whispering together, so I thought this a logical place to step in and clarify what was going on. I asked them if they had any questions. They shook their heads no and giggled.
I sketched out a two-dimensional array where we would store the deck of cards. I assigned the “2” cards to row 1 and worked my way up to the Aces, which was in row 13. I then wrote the numbers 1 to 4 at the tops of the columns (which I had cleverly arranged in the suit hierarchy of Clubs, Diamonds, Hearts, then Spades, so that Clubs was in the lowest numbered column and Spades the highest.) I now had all the cards in a deck arranged in a two dimensional pattern that happened (by design) to mirror the relative value of the cards and suits. The two of Clubs, the lowest ranking card in a full deck, was in position 1,1. The Ace of Spades occupied the highest value box: 13,4.
I explained that with this array, not only did we know what a deck of cards looked like, from a computer’s point of view, but we had, at the same time, established the relative values of each card in the deck simply by its position in the array (by concatenating the two numbers that made up the array coordinates. So, the two of Clubs would be worth 11 (from position 1,1) and the Ace of Spaces comes out to 134. The values of the cards with face values of 7 would be 61, 62, 63, 64; while the cards with a face value of 9 would be 81, 82, 83, 84 respectively. Thus any card with a face value of 9 was worth more than any card with a face value of 7, but a 9 of spades was worth more than a 9 of diamonds.)
Before going on to define the relative value of different combinations of five cards by assigning values to different configurations, it was time to ensure that they got the concept. So, I asked them to evaluate different pairs of cards and determine which had the higher value. I thought this was pretty straight-forward. All they had to do was find the card by its numeric order and suit on the array, create its “value” by concatenating the coordinates and compare the result to the value of another card. For example: which is worth more: the Ace of Hearts (133) or the Jack of Diamonds (112)? They were hopelessly lost.
I gave them a number of such questions and asked them to work in groups while I went around to see what was going on. I was startled to get questions like, “What’s a J?” and “What’s the difference between spades and clubs?” The light slowly turned on in my head: Arabs do not play cards. Most of them had probably never seen a deck of cards before, let alone become familiar with the values and suits.
Realizing my god-awful mistake and knowing that I had just wasted a good hour of class time as well as probably offended the students who I hadn’t simply baffled, I sent them on a break while I tried to gather my thoughts and figure out a different approach to teaching them the purpose and some of the applications of arrays. I was thankful that the curriculum covered only two-dimensional arrays and not 3-, 4-, 5-, or x-dimensional ones.
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