In article <opsh8wwchn5a2sq9@digitalmars.com>, Regan Heath says...
>
>On Mon, 29 Nov 2004 19:45:07 +0000 (UTC), <alexander.panek@brainsware.org> wrote:
>> In article <cofq5q$18dv$1@digitaldaemon.com>, Chris Sauls says...
>>>
>>> In article <cofnsm$1510$1@digitaldaemon.com>,
>>> alexander.panek@brainsware.org
>>> says...
>>>>
>>>> Hello,
>>>>
>>>> I got a problem with an array of structs in a class: when I declare
>>>> the array
>>>> inside the class as static, everything works fine. But as soon as I
>>>> try to
>>>> handle that with a dynamical array it tells me "Error: ArrayBoundsError
>>>> <file(line)>". Is there no way to use dynamic arrays of structs? or
>>>> did I just
>>>> misused that?
>>>>
>>>> struct foo {
>>>> char[] x;
>>>> }
>>>>
>>>> class bar {
>>>> private foo [] y;
>>>>
>>>> this() { foo[0].x = "hello world"; } // <--- there i get the error
>>>> }
>>>>
>>>
>>> The problem here is a simple but common one.  You are attempting to
>>> access the
>>> first value in a set with /zero/ items.  Here are a couple of correct
>>> examples:
>>>
>>> this() {
>>> foo ~= "hello world";
>>> }
>>>
>>>
>>> this() {
>>> foo.length = 1;
>>> foo[0] = "hello world";
>>> }
>>>
>>> Even dynamic arrays have to be told their length before using them.
>>> I'm fond of
>>> the first method (concatenation) myself, but there are times when the
>>> second
>>> method is best.  Experimentation will pay off here.
>>>
>>> -- Chris Sauls
>>>
>>>
>>
>> Well. I tried those and neither the '~='-operater helped, nor is the
>> length-property available for an array of structs. Shall I use an array
>> of
>> pointers instead of dynamic arrays or just a pointer for that? Maybe that
>> helps..gonna try.
>>
>> And before I forget:
>>
>> <code>
>>>> struct foo {
>>>> char[] x;
>>>> }
>>>>
>>>> class bar {
>>>> private foo [] y;
>>>>
>>>> this() { y[0].x = "hello world"; } // <--- there i get the error
>>>> }
>> </code>
>>
>> better? :P
>
>Both 'x' and 'y' are dynamic arrays.
>Both require you to explicitly extend the length of them, or, use the
>append operator '~'.
>
>Example:
>
>import std.stdio;
>
>struct foo {
>   char[] x;
>}
>
>version(EXTEND) {
>	class bar {
>	  private foo[] y;
>	  this() {
>		foo f;
>		writef("EXTEND\n");
>		f.x = "hello world";
>		y ~= f;
>	  }
>	}
>}
>else {
>	class bar {
>	  private foo[] y;
>	  this() {
>	    foo f;
>	    writef("APPEND\n");
>	    f.x = "hello world";
>	    y.length = y.length + 1;
>	    y[y.length-1] = f;
>	  }
>	}
>}
>
>void main()
>{
>   bar b = new bar();
>   writef(b.y[0].x,"\n");
>}
>
>compile with:
>   "dmd dynamic.d" for the append version
>   "dmd dynamic.d -version=EXTEND" for the extend version
>
>Also note that:
>   y[y.length-1] = f;
>
>copies the 'f' foo structure into the array, which isn't a problem unless the struct is large in which case it is slower than using a class (which is a reference type thus all you copy is the reference to the class, not the actual class itself).
>
>If you want speed and to use a struct then consider a struct pointer i.e.
>
>struct foo {
>   char[] x;
>}
>
>class bar {
>   private foo*[] y;
>   this() {
>     foo *f = new foo();
>     f.x = "hello world";
>     y ~= f;
>   }
>}
>
>Regan
>
>-- 
>Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/


I thank you very much! First really helpful message! Works now! :)

Alex

On Mon, 29 Nov 2004 17:56:38 +0000 (UTC), alexander.panek@brainsware.org
wrote:

> struct foo {
> char[] x;
> }
> 
> class bar {
> private foo [] y;
> 
> this() { foo[0].x = "hello world"; } // <--- there i get the error
> }

This worked for me ...

<code>
import std.stdio;
struct foo {
char[] x;
}

class bar {
    private foo [] y;

    this()
    {
        y.length = 1;

        y[0].x ~= "hello world";
    }
}

void main()
{
    bar B = new bar;
    writefln("%s\n", B.y[0].x);
}

</code>
-- 
Derek
Melbourne, Australia
30/11/2004 9:11:42 AM

In article <cofu83$1ee2$1@digitaldaemon.com>, alexander.panek@brainsware.org says...
>
>Well. I tried those and neither the '~='-operater helped, nor is the length-property available for an array of structs. Shall I use an array of pointers instead of dynamic arrays or just a pointer for that? Maybe that helps..gonna try.
>
>Thanks, Alex
>

Both the concat. operator and length prop. will work Ok like so:

>import std.stream;
>import std.string;
>
>struct foo {
>    char[] x;
>}
>
>class bar {
>    private foo[] y;
>    this()
>    {
>        y ~= new foo[1];
>        y[0].x = "hello world";
>    }
>    this(int x)
>    {
>        y.length = x;
>        foreach(int idx, inout foo f; y) {
>            f.x = "hello world (" ~ std.string.toString(idx) ~ ")";
>        }
>    }
>}
>
>void main()
>{
>    {
>        bar B = new bar;
>        stdout.writefln(B.y[0].x);
>    }
>    {
>        bar B = new bar(100);
>        foreach(foo f; B.y) {
>            stdout.writefln(f.x);
>        }
>    }
>}

- Dave

Derek Parnell wrote:
> class bar {
>     private foo [] y;
> 
>     this()     {
>         y.length = 1;
>                 y[0].x ~= "hello world";     }
> }

Wouldn't
	y[0].x = "hello world";
work just as well, since x is empty?

On Mon, 29 Nov 2004 17:26:35 -0700, Russ Lewis wrote:

> Derek Parnell wrote:
>> class bar {
>>     private foo [] y;
>> 
>>     this()
>>     {
>>         y.length = 1;
>> 
>>         y[0].x ~= "hello world";
>>     }
>> }
> 
> Wouldn't
> 	y[0].x = "hello world";
> work just as well, since x is empty?

Yep, sure would. I guess I was just being a bit paranoid wanting to ensure that a copy of the string was assigned rather than just a reference. But a simple '=' does that in this context anyway.

-- 
Derek
Melbourne, Australia
30/11/2004 2:13:15 PM

alexander.panek@brainsware.org wrote:
<snip>
[ArrayBoundsError]
> struct foo {
> char[] x;
> }
> 
> class bar {
> private foo [] y;
> 
> this() { foo[0].x = "hello world"; } // <--- there i get the error
> }
<snip>

Unless I'm missing something, it can only be a bug that this compiles. What does DMD think it means?

(I haven't tested it in 0.107 yet.)

Stewart.

-- 
My e-mail is valid but not my primary mailbox.  Please keep replies on the 'group where everyone may benefit.

On Tue, 30 Nov 2004 10:28:39 +0000, Stewart Gordon <smjg_1998@yahoo.com> wrote:

> alexander.panek@brainsware.org wrote:
> <snip>
> [ArrayBoundsError]
>> struct foo {
>> char[] x;
>> }
>>  class bar {
>> private foo [] y;
>>  this() { foo[0].x = "hello world"; } // <--- there i get the error
>> }
> <snip>
>
> Unless I'm missing something, it can only be a bug that this compiles. What does DMD think it means?
>
> (I haven't tested it in 0.107 yet.)
>
> Stewart.
>

1.07 gives:
bugtest.d(8): no [] operator overload for type foo

-- 
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Salesforce.com and Oracle customers." - www.microsoft-watch.com:
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complaint with my local member asking why such an unsafe
environment should be allowed to continue, tradition or not."
- http://www.sydneyanglicans.net/culture/watching/alien_vs_predator/

Derek Parnell wrote:
> On Mon, 29 Nov 2004 17:26:35 -0700, Russ Lewis wrote:
>>Wouldn't
>>	y[0].x = "hello world";
>>work just as well, since x is empty?
> 
> Yep, sure would. I guess I was just being a bit paranoid wanting to ensure
> that a copy of the string was assigned rather than just a reference. But a
> simple '=' does that in this context anyway.

Well, if you really want to make sure that you are assiging a copy, then
	y[0].x = "hello world".dup;
should work.