I work a lot with C functions, many of which yield pointer + length.

Is there a way to cast this or materialize a D-style array backed by the already allocated data (with length) to avoid copies which slow things down?

I recognize memory management is a complication. Typically, I would be responsible for free'ing the array later.

Thanks in advance

On 02.05.19 22:03, James Blachly wrote:
> I work a lot with C functions, many of which yield pointer + length.
> 
> Is there a way to cast this or materialize a D-style array backed by the already allocated data (with length) to avoid copies which slow things down?

Just slice the pointer with the length:

    int* ptr;
    size_t len;
    int[] arr = ptr[0 .. len];

On 5/2/19 4:05 PM, ag0aep6g wrote:
> Just slice the pointer with the length:
> 
>      int* ptr;
>      size_t len;
>      int[] arr = ptr[0 .. len];

Perfect thanks. I searched but without using the magic word "slice" I couldn't find meaningful results.

Thanks again.

On 05/02/2019 08:21 PM, James Blachly wrote:
> On 5/2/19 4:05 PM, ag0aep6g wrote:
>> Just slice the pointer with the length:
>>
>>      int* ptr;
>>      size_t len;
>>      int[] arr = ptr[0 .. len];
> 
> Perfect thanks. I searched but without using the magic word "slice" I couldn't find meaningful results.
> 
> Thanks again.

Looks like I indexed it under "slice from pointer":


http://ddili.org/ders/d.en/pointers.html#ix_pointers.slice%20from%20pointer

Ali

On 5/3/19 5:42 AM, Ali Çehreli wrote:
> On 05/02/2019 08:21 PM, James Blachly wrote:
>> On 5/2/19 4:05 PM, ag0aep6g wrote:
>>> Just slice the pointer with the length:
>>>
>>>      int* ptr;
>>>      size_t len;
>>>      int[] arr = ptr[0 .. len];
>>
>> Perfect thanks. I searched but without using the magic word "slice" I couldn't find meaningful results.
>>
>> Thanks again.
> 
> Looks like I indexed it under "slice from pointer":
> 
> 
> http://ddili.org/ders/d.en/pointers.html#ix_pointers.slice%20from%20pointer
> 
> Ali
> 

Thanks Ali, also helpful examples!