• Andrea Fontana (5/5) Feb 20 2014 I'm pretty sure I've just read about this, but search engines are
• bearophile (5/8) Feb 20 2014 One way to do it (untested):
• Andrea Fontana (2/10) Feb 20 2014 Ok, so it seems there's no "built-in" ways...
• bearophile (4/5) Feb 20 2014 Yeah, and this is a very good thing :-)
• Dicebot (6/20) Feb 20 2014 You can't do it without allocation because memory layout is
• Chris Williams (8/12) Feb 21 2014 You should only have to copy the top list, though.
• Chris Williams (3/15) Feb 21 2014 Addendum: Note that bearophile's code probably works out to the

"Andrea Fontana" <nospam example.com> writes:

I'm pretty sure I've just read about this, but search engines are 
not useful in this case.

I have a C api that need a int** params that represent a int[][]. 
How can I convert from d to c to pass it? For simple arrays, 
array.ptr seems to work...

"bearophile" <bearophileHUGS lycos.com> writes:

Andrea Fontana:

 I have a C api that need a int** params that represent a 
 int[][]. How can I convert from d to c to pass it? For simple 
 arrays, array.ptr seems to work...

One way to do it (untested):

int** pp = myDArray.map!(a => a.ptr).array.ptr;

Bye,
bearophile

"Andrea Fontana" <nospam example.com> writes:

On Thursday, 20 February 2014 at 16:47:43 UTC, bearophile wrote:
 Andrea Fontana:

 I have a C api that need a int** params that represent a 
 int[][]. How can I convert from d to c to pass it? For simple 
 arrays, array.ptr seems to work...

 One way to do it (untested):

 int** pp = myDArray.map!(a => a.ptr).array.ptr;

 Bye,
 bearophile

Ok, so it seems there's no "built-in" ways...

"bearophile" <bearophileHUGS lycos.com> writes:

Andrea Fontana:

 Ok, so it seems there's no "built-in" ways...

Yeah, and this is a very good thing :-)

Bye,
bearophile

"Dicebot" <public dicebot.lv> writes:

On Thursday, 20 February 2014 at 16:55:51 UTC, Andrea Fontana 
wrote:
 On Thursday, 20 February 2014 at 16:47:43 UTC, bearophile wrote:
 Andrea Fontana:

 I have a C api that need a int** params that represent a 
 int[][]. How can I convert from d to c to pass it? For simple 
 arrays, array.ptr seems to work...

 One way to do it (untested):

 int** pp = myDArray.map!(a => a.ptr).array.ptr;

 Bye,
 bearophile

 Ok, so it seems there's no "built-in" ways...

You can't do it without allocation because memory layout is 
different for int** and int[][] in D - are.ptr in latter points 
to slice struct (pointer+length) as opposed to raw pointer in 
former.

"Chris Williams" <yoreanon-chrisw yahoo.co.jp> writes:

On Thursday, 20 February 2014 at 17:02:15 UTC, Dicebot wrote:
 You can't do it without allocation because memory layout is 
 different for int** and int[][] in D - are.ptr in latter points 
 to slice struct (pointer+length) as opposed to raw pointer in 
 former.

You should only have to copy the top list, though.

int*[] temp = new int*[ arr.length ];
for (size_t i = 0; i < arr.length; i++) {
     temp[i] = arr[i].ptr;
}
int** output = temp.ptr;

Untested.

"Chris Williams" <yoreanon-chrisw yahoo.co.jp> writes:

On Friday, 21 February 2014 at 19:13:13 UTC, Chris Williams wrote:
 On Thursday, 20 February 2014 at 17:02:15 UTC, Dicebot wrote:
 You can't do it without allocation because memory layout is 
 different for int** and int[][] in D - are.ptr in latter 
 points to slice struct (pointer+length) as opposed to raw 
 pointer in former.

 You should only have to copy the top list, though.

 int*[] temp = new int*[ arr.length ];
 for (size_t i = 0; i < arr.length; i++) {
     temp[i] = arr[i].ptr;
 }
 int** output = temp.ptr;

 Untested.

Addendum: Note that bearophile's code probably works out to the 
same thing.