From The D Programming Language, arrays section:  Is this last bit about  b = a[0 .. a.length]  true, or should it actually be  b = a[0 .. a.length-1] ?   In other words, are ranges inclusive, or not?

Sean


Slicing
Slicing an array means to specify a subarray of it. For example:
	int a[10];	declare array of 10 ints
	int b[];

	b = a[1..3];	a[1..3] is a 3 element array consisting of
			a[1], a[2], and a[3]

The [] is shorthand for a slice of the entire array. For example, the
assignments to b:
	int a[10];
	int b[]

	b = a;
	b = a[];
	b = a[0 .. a.length];

are all semantically equivalent.

"Sean L. Palmer" <spalmer@iname.com> wrote in message news:9tai22$1fok$1@digitaldaemon.com...
> From The D Programming Language, arrays section:  Is this last bit about
b
> = a[0 .. a.length]  true, or should it actually be  b = a[0 .. a.length-1] ?   In other words, are ranges inclusive, or not?

    "s[0..4] = ...  // error, only 3 elements in s"

So ranges are inclusive, and you get an exception if
you write s[0..s.length].

"Sean L. Palmer" <spalmer@iname.com> wrote in message news:9tai22$1fok$1@digitaldaemon.com...
> From The D Programming Language, arrays section:  Is this last bit about
b
> = a[0 .. a.length]  true, or should it actually be  b = a[0 .. a.length-1]

a[0..a.length] is it.

8-0

This is a Bad Thing, IMHO.  The .length property should give the *length* of the array, not the maximum index!  You could add a maximum index property, though:

b = a[0..a.length-1];  // ok
b = a[0..a.length];  // ArrayOutOfBoundsException
b = a[0..a.maxIndex]; // ok

Or, perhaps better yet, you could just allow unbounded slicing, which goes to the edges:

b = a[0..];
b = a[..a.maxIndex];
b = a[..]; // all 3 of these are identical



Walter wrote:

> "Sean L. Palmer" <spalmer@iname.com> wrote in message news:9tai22$1fok$1@digitaldaemon.com...
> > From The D Programming Language, arrays section:  Is this last bit about
> b
> > = a[0 .. a.length]  true, or should it actually be  b = a[0 .. a.length-1]
>
> a[0..a.length] is it.

--
The Villagers are Online! villagersonline.com

.[ (the fox.(quick,brown)) jumped.over(the dog.lazy) ]
.[ (a version.of(English).(precise.more)) is(possible) ]
?[ you want.to(help(develop(it))) ]

But the length is not the maximum index.

"Russ Lewis" <spamhole-2001-07-16@deming-os.org> wrote in message news:3BF94B93.6D0C72FF@deming-os.org...
> 8-0
>
> This is a Bad Thing, IMHO.  The .length property should give the *length*
of the
> array, not the maximum index!  You could add a maximum index property,
though:
>
> b = a[0..a.length-1];  // ok
> b = a[0..a.length];  // ArrayOutOfBoundsException
> b = a[0..a.maxIndex]; // ok
>
> Or, perhaps better yet, you could just allow unbounded slicing, which goes
to
> the edges:
>
> b = a[0..];
> b = a[..a.maxIndex];
> b = a[..]; // all 3 of these are identical
>
>
>
> Walter wrote:
>
> > "Sean L. Palmer" <spalmer@iname.com> wrote in message news:9tai22$1fok$1@digitaldaemon.com...
> > > From The D Programming Language, arrays section:  Is this last bit
about
> > b
> > > = a[0 .. a.length]  true, or should it actually be  b = a[0 ..
a.length-1]
> >
> > a[0..a.length] is it.
>
> --
> The Villagers are Online! villagersonline.com
>
> .[ (the fox.(quick,brown)) jumped.over(the dog.lazy) ]
> .[ (a version.of(English).(precise.more)) is(possible) ]
> ?[ you want.to(help(develop(it))) ]
>
>

"Pavel Minayev" <evilone@omen.ru> wrote in message news:9tbc2a$1vm1$1@digitaldaemon.com...
> "Sean L. Palmer" <spalmer@iname.com> wrote in message news:9tai22$1fok$1@digitaldaemon.com...
> > From The D Programming Language, arrays section:  Is this last bit about
> b
> > = a[0 .. a.length]  true, or should it actually be  b = a[0 ..
a.length-1]
> > ?   In other words, are ranges inclusive, or not?
>
>     "s[0..4] = ...  // error, only 3 elements in s"
>
> So ranges are inclusive, and you get an exception if
> you write s[0..s.length].

s[0..4] has 4 elements: s[0], s[1], s[2], s[3]

Walter wrote:
> 
> s[0..4] has 4 elements: s[0], s[1], s[2], s[3]

So array-slice ranges are half-open, yes? Your first slice example in the spec says:

	b = a[1..3];	a[1..3] is a 3 element array consisting of
			a[1], a[2], and a[3]


Should this read "a 2 element array consisting of a[1] and a[2]"?

This kind of ranging is going to piss off C programmers; this thread being case in point.

-RB

"Russell Borogove" <kaleja@estarcion.com> wrote in message news:3BF9CD48.E638FD8@estarcion.com...
>
>
> Walter wrote:
> >
> > s[0..4] has 4 elements: s[0], s[1], s[2], s[3]
>
> So array-slice ranges are half-open, yes? Your first slice example in the spec says:
>
> b = a[1..3]; a[1..3] is a 3 element array consisting of a[1], a[2], and a[3]

Looks like the spec is wrong <g>.

> This kind of ranging is going to piss off C programmers; this thread being case in point.

First I have to get the documentation right.

"Walter" <walter@digitalmars.com> wrote in message news:9tche0$2n2v$3@digitaldaemon.com...

> But the length is not the maximum index.

Then [0..length] is not legal.

"Pavel Minayev" <evilone@omen.ru> wrote in message news:9tcv3f$2vca$1@digitaldaemon.com...
> "Walter" <walter@digitalmars.com> wrote in message news:9tche0$2n2v$3@digitaldaemon.com...
>
> > But the length is not the maximum index.
>
> Then [0..length] is not legal.

I don't understand what you're driving at, then.