• Heinz <malagana15 yahoo.es> Feb 08 2009
• "Denis Koroskin" <2korden gmail.com> Feb 08 2009
• Burton Radons <burton.radons gmail.com> Feb 08 2009
• Robert Fraser <fraserofthenight gmail.com> Feb 08 2009

Heinz <malagana15 yahoo.es> writes:

Hi,

I remember i read around the D site that dinamic arrays can be stored in system
memory in a 'non contiguous' way (different locations). I was trying to find
again that page but haven't had any lucky. I'm not crazy, i know i saw it.

Anyway, i need this info to ensure that i can/can't cast from void[] to void*.
I'm working with D dinamic arrays but i need to work this data then with
windows API's, these functions take void* as parameters. I pass params of type
cast(void*)void[] and have had no problems at the moment. But, what if data in
the array is not stored contiguously? windows functions will crash right?

I hope you get the idea, and i hope someone to answer me. Thanx.

"Denis Koroskin" <2korden gmail.com> writes:

On Mon, 09 Feb 2009 00:25:41 +0300, Heinz <malagana15 yahoo.es> wrote:

 Hi,

 I remember i read around the D site that dinamic arrays can be stored in  
 system memory in a 'non contiguous' way (different locations). I was  
 trying to find again that page but haven't had any lucky. I'm not crazy,  
 i know i saw it.


Never heard that.

 Anyway, i need this info to ensure that i can/can't cast from void[] to  
 void*. I'm working with D dinamic arrays but i need to work this data  
 then with windows API's, these functions take void* as parameters. I  
 pass params of type cast(void*)void[] and have had no problems at the  
 moment. But, what if data in the array is not stored contiguously?  
 windows functions will crash right?

 I hope you get the idea, and i hope someone to answer me. Thanx.


No need to cast:

void[] array = ...;
void* ptr = array.ptr;

Burton Radons <burton.radons gmail.com> writes:

Heinz Wrote:

 I remember i read around the D site that dinamic arrays can be stored in
system memory in a 'non contiguous' way (different locations). I was trying to
find again that page but haven't had any lucky. I'm not crazy, i know i saw it.


It could have meant that arrays might be extended by allocating more pages onto
the end as needed and as possible - the physical location of these pages would
be non-contiguous, but they'd be contiguous in the memory view. Any other way
would be replicating processor features in software, so I don't see it
happening.

Robert Fraser <fraserofthenight gmail.com> writes:

Heinz wrote:
 Hi,
 
 I remember i read around the D site that dinamic arrays can be stored in
system memory in a 'non contiguous' way (different locations). I was trying to
find again that page but haven't had any lucky. I'm not crazy, i know i saw it.
 
 Anyway, i need this info to ensure that i can/can't cast from void[] to void*.
I'm working with D dinamic arrays but i need to work this data then with
windows API's, these functions take void* as parameters. I pass params of type
cast(void*)void[] and have had no problems at the moment. But, what if data in
the array is not stored contiguously? windows functions will crash right?
 
 I hope you get the idea, and i hope someone to answer me. Thanx.


Dynamic arrays are guaranteed to be stored contiguously (possibly it was 
a suggestion?). Casting to void* should work fine, but to be more 
portable, you should use (cast(void*) arr.ptr) (in case in future 
versions or on different platforms, the ptr and length feilds are reversed)