101–110 of 344 posts
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Compile it, look at the assembly. You can know. The answer will vary from place to place, but it isn't non-existent.
And then you update your compiler and something completely different happens.
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> So the answer is "Undefined." The code is undefined, but "I don't know." is still the correct answer for what happens to the variable.
> The code is undefined, but "I don't know." is still the correct answer for what happens to the variable. Well, then a better choice would be "I can't know."
"I dont know" was absolutely the correct answer.
I found it an amusing excrcise, if not terribly relevant, even as someone who spends 90% of his dev time in C. What rubs me about these sorts of articles is they make some presumption about the importance and nessecisity of writing truely portable C, as if the "C Standard" were in and of itself a terribly useful tool. This is in contrast to where I live most of the time which is "GCC as an assembler macro language" (…
Not necessarily, I took it to mean that engineering is holistic and things like compiler behavior in the face of undefined parts of the standard are important to account for.
I found it an amusing excrcise, if not terribly relevant, even as someone who spends 90% of his dev time in C. What rubs me about these sorts of articles is they make some presumption about the importance and nessecisity of writing truely portable C, as if the "C Standard" were in and of itself a terribly useful tool. This is in contrast to where I live most of the time which is "GCC as an assembler macro language" (…
"So standards are not some kind of holy book that has to be revered. Standards too need to be questioned."
The way I see it, a lot of compiler writers are basically taking the standard as gospel and ignoring everything else "because the standard doesn't say we can't" --- and that's a huge problem, because behaviour that the standard doesn't define often has a far more common-sense meaning that programmers expect. IMHO the onus should really be on the authors of compilers to find that reasonable meaning. In fact, the standard even suggests that one possible undefined behaviour is something like "behave in a manner characteristic of the environment" (can't remember nor be bothered looking up the standard.)
There are a few problems with the questionnaire. "I don't know" is pretty generic choice to be given/choosen. Say for example, in question 5, the statement "return i++ + ++i;" is undefined, because the value of i is read and modified twice in a single sequence point (and of course, the order of addition is unspecified), which is not allowed in C. So the answer is "Undefined." (The explanation given in the page not ac…
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Switch the compiler to ARM, which is as "typical modern arch" as it gets, and see for yourself.
I don't think it's surprising when you switch machine architecture and/or word sizes that you get different results. In fact for me, that's completely normal and to be expected.
I'd like these things to be listed and marked "implementation defined", personally.
I found it an amusing excrcise, if not terribly relevant, even as someone who spends 90% of his dev time in C. What rubs me about these sorts of articles is they make some presumption about the importance and nessecisity of writing truely portable C, as if the "C Standard" were in and of itself a terribly useful tool. This is in contrast to where I live most of the time which is "GCC as an assembler macro language" (…
It's very much worth reading, Linus Torvalds' opinion of standards that's linked in that article, but I'll link it again here: https://lkml.org/lkml/2018/6/5/769 "So standards are not some kind of holy book that has to be revered. Standards too need to be questioned." The way I see it, a lot of compiler writers are basically taking the standard as gospel and ignoring everything else "because the standard doesn't say…
I would be rather disappointed if they didn't, honestly.
If we're going to be --pedantic, shouldn't the author specify the exact standard of the C language under test? A lot of companies have varying implementations of C and perhaps some do specify some of the behavior at hand here.