The name of a variable is really a symbolic name for its address in memory, he said. And the “type” of the data says how much space it occupies: characters get one byte; the size of integers and floating-point numbers (numbers with decimal places) is determined by the particular hardware. There are also long integers and short ones, he said, and double-precision floating-point types. And the difference is their size in memory. So the declaration of the variable, he concluded, allocates space in memory, at a particular location, with a particular width in bytes, the symbolic name simply pointing to the beginning of where it lives.
This information had a startling effect on me. All those variable names I had seen strewn across the code—wincount, filename, user_id—were suddenly revealed as conveniences, human-readable words, whose true form was a series of bits indicating where in the machine’s memory the value of the variable could be found. It’s one thing to think you know that there is something called computer “memory”; it was quite another for me to understand how it related, precisely, to the text of the program. For the first time, I understood there was a mapping between the symbolic words of the code and the physical existence of the machine. And something in me shifted. I decided I already knew far too much about words—fifteen linguistics-practicing years of thinking and wondering over and studying words. Now I wanted to know more about the machine.
I began reading ahead in the book. I took it home, read it late at night, enjoyed the conversational, collegial style of Kernighan and Ritchie as they described the language they had created, the language in which the UNIX operating system itself was written. I began looking forward to my skinny-bearded-man, to the next topic on the videotape. I began losing track of other things: I was late paying bills, left novels with the bookmark stalled halfway, forgot to return phone calls to friends. When James made two trips home, I was glad to see him but not sorry to see him go. I suppose the world was going on as it usually did—half a million Iranian troops were still poised to invade Iraq, Russian troops kept battling the mujahideen in Afghanistan, civil war raged on in El Salvador, Gloria Steinem inexorably turned fifty, the fleshy face of Democratic presidential hopeful Walter Mondale began appearing on the covers of the newsweeklies—but little of it reached me. I was learning about structures.