Learn to Say, “Hello, World”
Thomas Guest
PAUL LEE, username leep, more commonly known as Hoppy, had a reputa- tion as the local expert on programming issues. I needed help. I walked across to Hoppy’s desk and asked whether he could take a look at some code for me.
“Sure,” said Hoppy, “pull up a chair.” I took care not to topple the empty cola cans stacked in a pyramid behind him.
“What code?”
“In a function in a file,” I said.
“So, let’s take a look at this function.” Hoppy moved aside a copy of K&R and slid his keyboard in front of me.
“Where’s the IDE?” Apparently, Hoppy had no IDE running, just some editor that I couldn’t operate. He grabbed back the keyboard. A few keystrokes later, we had the file open—it was quite a big file—and were looking at the function—it was quite a big function. He paged down to the conditional block I wanted to ask about.
“What would this clause actually do if x is negative?” I asked. “Surely it’s wrong.”
I’d been trying all morning to find a way to force x to be negative, but the big function in the big file was part of a big project, and the cycle of recompil- ing and then rerunning my experiments was wearing me down. Couldn’t an expert like Hoppy just tell me the answer?
??102 97 Things Every Programmer Should Know
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???????????????Hoppy admitted he wasn’t sure. To my surprise, he didn’t reach for K&R. Instead, he copied the code block into a new editor buffer, reindented it, wrapped it up in a function. A short while later, he had coded up a main func- tion that looped forever, prompting the user for input values, passing them to the function, printing out the result. He saved the buffer as a new file, tryit.c. All of this I could have done for myself, though perhaps not as quickly. But his next step was wonderfully simple and, at the time, quite foreign to my way of working:
$ cc tryit.c && ./a.out
Look! His actual program, conceived just a few minutes earlier, was now up and running. We tried a few values and confirmed my suspicions (so I’d been right about something!) and then he cross-checked the relevant section of K&R. I thanked Hoppy and left, again taking care not to disturb his cola can pyramid.
Back at my own desk, I closed down my IDE. I’d become so used to working on a big project within a big product that I’d started to think that was what I should be doing. A general-purpose computer can do little tasks, too. I opened a text editor and began typing:
#include <stdio.h>
int main()
{
printf("Hello, World\n");
return 0;
}