I'm trying to make a multidimensional array. I feel I've tried every thing. Is there a good guide explaining it?

struct Spot { bool dot; }
spots = new Spot[][](800,600);
	assert(spots[800-1][600-1].dot, "Out of bounds");

On Sunday, 28 September 2014 at 04:24:25 UTC, Joel wrote:
> I'm trying to make a multidimensional array. I feel I've tried every thing. Is there a good guide explaining it?
>
> struct Spot { bool dot; }
> spots = new Spot[][](800,600);
> 	assert(spots[800-1][600-1].dot, "Out of bounds");

dot is initialized to false, then the assertion fails. But your assertion message leads to think that there is a bound error, which is not the case, the
assertion fails because you're expecting dot to be true:

----
import std.stdio;

void main(string args[])
{
    struct Spot { bool dot; }
    auto spots = new Spot[][](800,600);

    writeln(spots);
	    assert(!spots[800-1][600-1].dot, "Out of bounds");
}
----

passes without failure. Actually the array size is OK.

On Sunday, 28 September 2014 at 04:38:56 UTC, JKPdouble wrote:
> On Sunday, 28 September 2014 at 04:24:25 UTC, Joel wrote:
>> I'm trying to make a multidimensional array. I feel I've tried every thing. Is there a good guide explaining it?
>>
>> struct Spot { bool dot; }
>> spots = new Spot[][](800,600);
>> 	assert(spots[800-1][600-1].dot, "Out of bounds");
>
> dot is initialized to false, then the assertion fails. But your assertion message leads to think that there is a bound error, which is not the case, the
> assertion fails because you're expecting dot to be true:
>
> ----
> import std.stdio;
>
> void main(string args[])
> {
>     struct Spot { bool dot; }
>     auto spots = new Spot[][](800,600);
>
>     writeln(spots);
> 	    assert(!spots[800-1][600-1].dot, "Out of bounds");
> }
> ----
>
> passes without failure. Actually the array size is OK.

I meant:
----
void main(string args[])
{
    struct Spot { bool dot; }
    auto spots = new Spot[][](800,600);

    assert(!spots[800-1][600-1].dot, "element dot is true");
}
----

On Sun, 28 Sep 2014 04:24:19 +0000
Joel via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:

> struct Spot { bool dot; }
> spots = new Spot[][](800,600);
btw, does anybody know why i can do `new ubyte[256];` but not `new ubyte[256][256];`? hate that.

On Sunday, 28 September 2014 at 04:24:25 UTC, Joel wrote:
> I'm trying to make a multidimensional array. I feel I've tried every thing. Is there a good guide explaining it?
>
> struct Spot { bool dot; }
> spots = new Spot[][](800,600);
> 	assert(spots[800-1][600-1].dot, "Out of bounds");

You could also take a look at unstd.multidimarray (not my work, but I'm using it extensively at the moment)[1].

[1] http://denis-sh.bitbucket.org/unstandard/unstd.multidimarray.html

On Sun, Sep 28, 2014 at 10:48:45AM +0300, ketmar via Digitalmars-d-learn wrote:
> On Sun, 28 Sep 2014 04:24:19 +0000
> Joel via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:
> 
> > struct Spot { bool dot; }
> > spots = new Spot[][](800,600);
> btw, does anybody know why i can do `new ubyte[256];` but not `new ubyte[256][256];`? hate that.

File a bug.


T

-- 
I see that you JS got Bach.

On 28/09/2014 08:48, ketmar via Digitalmars-d-learn wrote:
> On Sun, 28 Sep 2014 04:24:19 +0000
> Joel via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:
>
>> struct Spot { bool dot; }
>> spots = new Spot[][](800,600);
> btw, does anybody know why i can do `new ubyte[256];` but not
> `new ubyte[256][256];`? hate that.

You can do `new ubyte[256][256]`, if the destination type is a ubyte[256][].  The reason is that you are performing an allocation of the form `new T[n]`, which means allocate an array of n instances of type T.  In this case, T is ubyte[256], which is a static array type.

Stewart.

-- 
My email address is valid but not my primary mailbox and not checked regularly.  Please keep replies on the 'group where everybody may benefit.

On Sun, 28 Sep 2014 07:40:23 -0700
"H. S. Teoh via Digitalmars-d-learn"
<digitalmars-d-learn@puremagic.com> wrote:

> File a bug.
https://issues.dlang.org/show_bug.cgi?id=13556

On Sun, 28 Sep 2014 22:33:40 +0100
Stewart Gordon via Digitalmars-d-learn
<digitalmars-d-learn@puremagic.com> wrote:

> You can do `new ubyte[256][256]`, if the destination type is a ubyte[256][].  The reason is that you are performing an allocation of the form `new T[n]`, which means allocate an array of n instances of type T.  In this case, T is ubyte[256], which is a static array type.
it's completely counterintuitive. either `new ubyte[256];` should be disallowed, or `new ubyte[256][256];` should work as i expect it to work.

it's the same thing as with const methods: `const A foo ()`. yes, 'const' is a method attribute here, but it's counterintuitive.

Thanks JKPdouble. I was hoping for a clear way to work multidimensional arrays out.