Re: question about nullptr

Tim Rentsch <tr.17687@z991.linuxsc.com> writes:

Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:

Hmm.  I like the idea of a type-agnostic way to express a "zero"
value, [but] C's use of 0 for all scalar types strikes me more as
an historical accident than a design feature.

>
I don't think it was an accident at all.  It was chosen to be
consistent with how if(), while(), !, ?:, and so forth, all act.
There is a very consistent design philosophy there.  Sometimes
people who come from a strong Pascal background don't like it,
but personally I find the C model easier and more convenient to
work with than the Pascal model.

In early C, int was in a very real sense the default type.  In B,
types weren't even explicit, and IIRC variables were effectively "of
type int", or more precisely a 16-bit PDP-11 word.  (I'm glossing
over some details of B, many of which I don't know).  In that
context 0 made sense as a general-purpose "zero" value.

Modern C has moved away from making int some kind of default
(though it hasn't entirely done so).

What I dislike is the fact that 0 is *both* of the specific type
int *and* is commonly used as a general-purpose scalar 0.

I accept it because it's the way the language is defined, but
IMHO it's perhaps not an historical accident (you're right, it was
deliberate), but more of an historical relic.

Which is why I use 0 for integers, '\0' for characters, 0.0 for
floating-point, and NULL (or nullptr if it's available) for pointers.
If there were some general-purpose zero token that *isn't* of a
specific type (I mentioned "{}" upthread), I'd probably use that.
But it's not enough of a problem that I'd necessarily advocate a
language change.  And if someone else consistently uses 0 in pointer
context, I'll waste about half a second being annoyed and then move on.

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */