Comment by _nalply | Hacker News Reader

Comment by _nalply | Hacker News Reader

Parent Full thread

Perhaps unsigned could help here with understanding.

unsigned means, don't use of an integer MSB as sign bit. __nonstring means, the byte array might not be terminated with a NUL byte.

So what happens if you use integers instead of byte arrays? I mean cast away unsigned or add unsigned. Of course these two areas are different, but one could try to design such features that they behave in similar ways where it makes sense.

I am unsure but it seems, if you cast to a different type you lose the conditions of the previous type. And "should this be legal", you can cast away a lot of things and it's legal. That's C.

But whatever because it's not implemented. This all is hypothetical. I understand GCC that they took the easier way. Type strictness is not C's forte.

> Perhaps unsigned could help here with understanding.

No, they're very different situations.

> unsigned means, don't use of an integer MSB as sign bit.

First: unsigned is a keyword. This fact is not insignificant.

But anyway, even assuming they were both keywords or both attributes: "don't use an MSB as a sign bit" makes sense, because the MSB otherwise is used as a sign bit.

> __nonstring means, the byte array might not be terminated with a NUL byte.

The byte array already doesn't have to contain a NUL character to begin with. It just so happens that you usually initialize it somewhere with an initializer that does, but it's already perfectly legal to strip that NUL away later, or to initialize it in a manner that doesn't include a NUL character (say, char a[1] = {'a'}). It doesn't really make sense to change the type to say "we now have a new type with the cool invariant that is... identical to the original type's."

> I understand GCC that they took the easier way. Type strictness is not C's forte.

People would want whatever they do to make sense in C++ too, FWIW. So if they introduce a type incompatibility, they would want it to avoid breaking the world in other languages that enforce them, even if C doesn't.

Reply on news.ycombinator.com