Re: using Unsized Arrays in Structures from d?
On Friday, 4 May 2018 at 15:37:28 UTC, ag0aep6g wrote:
On Friday, 4 May 2018 at 13:02:08 UTC, NewUser wrote:
How can I use the following c structure from d.
struct Item
{
int id;
};
struct Group
{
int i;
int item_count;
struct Item items[];
};
tried defining items[] as both "Item[] items" and "Item*
items" in d, it compiles okay but gives an error when trying
to access it.
Here is the error.
object.Error@(0): Access Violation
In the C code, the elements of `items` are directly part of the
struct. There is no indirection. D doesn't have dedicated
syntax for this, but you can hint at it with a zero-sized array:
struct Group
{
int i;
int item_count;
Item[0] items;
}
Then access an item with `group.items.ptr[index]`.
Hi ag0aep6g,
Thanks a lot for that.
I should have thought of that (i would still have missed the .ptr
part), the old c syntax for the same thing used to be "Item
items[0]".
Thanks,
NewUser
Re: using Unsized Arrays in Structures from d?
On Friday, 4 May 2018 at 13:02:08 UTC, NewUser wrote:
How can I use the following c structure from d.
struct Item
{
int id;
};
struct Group
{
int i;
int item_count;
struct Item items[];
};
tried defining items[] as both "Item[] items" and "Item* items"
in d, it compiles okay but gives an error when trying to access
it.
Here is the error.
object.Error@(0): Access Violation
In the C code, the elements of `items` are directly part of the
struct. There is no indirection. D doesn't have dedicated syntax
for this, but you can hint at it with a zero-sized array:
struct Group
{
int i;
int item_count;
Item[0] items;
}
Then access an item with `group.items.ptr[index]`.
Re: using Unsized Arrays in Structures from d?
On Friday, 4 May 2018 at 14:55:18 UTC, Timoses wrote: On Friday, 4 May 2018 at 13:27:03 UTC, NewUser wrote: Hi Timoses, The structure is being returned from c and I'd like use it from d. What you have work perfectly when assigning from d. Regards, NewUser Then you probably need some `extern(C)` statement introducing the C function and the struct type, right? You could also try dstep to "translate" the C header file to D: https://github.com/jacob-carlborg/dstep Hi Timoses, Thanks for the suggestion, i'll try it out. Regards, NewUser
Re: using Unsized Arrays in Structures from d?
On Friday, 4 May 2018 at 13:27:03 UTC, NewUser wrote: Hi Timoses, The structure is being returned from c and I'd like use it from d. What you have work perfectly when assigning from d. Regards, NewUser Then you probably need some `extern(C)` statement introducing the C function and the struct type, right? You could also try dstep to "translate" the C header file to D: https://github.com/jacob-carlborg/dstep
Re: using Unsized Arrays in Structures from d?
On Friday, 4 May 2018 at 13:21:53 UTC, Timoses wrote:
On Friday, 4 May 2018 at 13:02:08 UTC, NewUser wrote:
tried defining items[] as both "Item[] items" and "Item*
items" in d, it compiles okay but gives an error when trying
to access it.
You were on the right track. D array notation is:
[] ;
For me this works:
```
struct Item
{
int id;
};
struct Group
{
int i;
int item_count;
Item[] items;
};
void main()
{
auto g = Group();
g.items ~= Item(3);
assert(g.items[0].id == 3);
}
```
Hi Timoses,
The structure is being returned from c and I'd like use it from d.
What you have work perfectly when assigning from d.
Regards,
NewUser
Re: using Unsized Arrays in Structures from d?
On Friday, 4 May 2018 at 13:02:08 UTC, NewUser wrote:
tried defining items[] as both "Item[] items" and "Item* items"
in d, it compiles okay but gives an error when trying to access
it.
You were on the right track. D array notation is:
[] ;
For me this works:
```
struct Item
{
int id;
};
struct Group
{
int i;
int item_count;
Item[] items;
};
void main()
{
auto g = Group();
g.items ~= Item(3);
assert(g.items[0].id == 3);
}
```
Re: using Unsized Arrays in Structures from d?
On Friday, 4 May 2018 at 13:02:08 UTC, NewUser wrote:
How can I use the following c structure from d.
struct Item
{
int id;
};
struct Group
{
int i;
int item_count;
struct Item items[];
};
tried defining items[] as both "Item[] items" and "Item* items"
in d, it compiles okay but gives an error when trying to access
it.
Here is the error.
object.Error@(0): Access Violation
The D equivalent is:
struct Item {
int id;
}
struct Group {
int i;
int item_count;
Item* items;
}
The error message you're getting makes me think items is null.
The lack of function names in the stack trace makes it kinda hard
to understand exactly what's happening - you can turn that on
with -g for DMD. Seeing some of the code that uses these structs
might also help.
--
Simen
using Unsized Arrays in Structures from d?
Hi,
How can I use the following c structure from d.
struct Item
{
int id;
};
struct Group
{
int i;
int item_count;
struct Item items[];
};
tried defining items[] as both "Item[] items" and "Item* items"
in d, it compiles okay but gives an error when trying to access
it.
Here is the error.
object.Error@(0): Access Violation
0x00BCA9D1
0x00BC104C
0x00BD01EB
0x00BD0169
0x00BD
0x00BCA827
0x74118654 in BaseThreadInitThunk
0x77534B17 in RtlGetAppContainerNamedObjectPath
0x77534AE7 in RtlGetAppContainerNamedObjectPath
Regards,
NewUser
