• Andre Pany (13/13) Jul 09 2018 Hi,
• Basile B. (7/21) Jul 09 2018 Hi, no it's not correct i think, right translation would be
• Andre Pany (8/15) Jul 09 2018 Thanks, it seems I also have to allocate the pointer before with
• Andre Pany (16/34) Jul 09 2018 If found this working, is this OK, or do I have a memory bug here?
• Kagamin (4/4) Jul 09 2018 const(char)*[] znames;
• Basile B. (13/31) Jul 09 2018 you don't need to allocate but to retrieve each string, do
• Basile B. (5/40) Jul 09 2018 Ok, i've read your other answers and it seems that you have a way
• Andre Pany (4/8) Jul 09 2018 Thanks a lot for your help.
• Kagamin (4/4) Jul 09 2018 Correct signature:
• Andre Pany (4/8) Jul 09 2018 Thank you, that looks great.

Andre Pany <andre s-e-a-p.de> writes:

Hi,

I need to call a C function within a DLL which has following 
signature:
   void GetParamNames (const char *paramNames[], size_t numParams);

The purpose of this function is to return a list of texts
I defined in D:
extern(C) GetParamNames (const char[]* paramNames, size_t 
numParams);

Is this correct? How can I call the function? I tried several 
possibilities but
always get a runtime crash.

Kind regards
André

Basile B. <b2.temp gmx.com> writes:

On Monday, 9 July 2018 at 10:33:03 UTC, Andre Pany wrote:
 Hi,

 I need to call a C function within a DLL which has following 
 signature:
   void GetParamNames (const char *paramNames[], size_t 
 numParams);

 The purpose of this function is to return a list of texts
 I defined in D:
 extern(C) GetParamNames (const char[]* paramNames, size_t 
 numParams);

 Is this correct? How can I call the function? I tried several 
 possibilities but
 always get a runtime crash.

 Kind regards
 André

Hi, no it's not correct i think, right translation would be

     extern(C) void GetParamNames(const char** paramNames, size_t 
numParams);

If you use the D array syntax you'll get into troubles because of 
ABI i think.

Baz.

Andre Pany <andre s-e-a-p.de> writes:

On Monday, 9 July 2018 at 10:38:54 UTC, Basile B. wrote:
 On Monday, 9 July 2018 at 10:33:03 UTC, Andre Pany wrote:
 Hi, no it's not correct i think, right translation would be

     extern(C) void GetParamNames(const char** paramNames, 
 size_t numParams);

 If you use the D array syntax you'll get into troubles because 
 of ABI i think.

 Baz.

Thanks, it seems I also have to allocate the pointer before with 
the numbers of numParams.
In python the code looks s.th. like this

self.output_names = (c_char_p * self.number_outputs)()

Do you know that is the equivalent in D?

Kind regards
André

Andre Pany <andre s-e-a-p.de> writes:

On Monday, 9 July 2018 at 10:56:18 UTC, Andre Pany wrote:
 On Monday, 9 July 2018 at 10:38:54 UTC, Basile B. wrote:
 On Monday, 9 July 2018 at 10:33:03 UTC, Andre Pany wrote:
 Hi, no it's not correct i think, right translation would be

     extern(C) void GetParamNames(const char** paramNames, 
 size_t numParams);

 If you use the D array syntax you'll get into troubles because 
 of ABI i think.

 Baz.

 Thanks, it seems I also have to allocate the pointer before 
 with the numbers of numParams.
 In python the code looks s.th. like this

 self.output_names = (c_char_p * self.number_outputs)()

 Do you know that is the equivalent in D?

 Kind regards
 André

If found this working, is this OK, or do I have a memory bug here?

         import core.stdc.stdlib: malloc, free;
         string[] result;

         size_t numOutputs = 4;
         const(char**) arr = cast (const(char**)) 
malloc(numOutputs * (char*).sizeof);

         auto status = GetParamNames(arr, numOutputs);

         for(int i = 0; i < numOutputs; i++)
         {
             const(char*) c = arr[i];
             result ~= c.fromStringz.dup;
         }

         free(cast(void*) arr);

Kind regards
André

Kagamin <spam here.lot> writes:

         const(char)*[] znames;
         znames.length=4;
         GetParamNames(znames.ptr, znames.length);
         const char[][] names=znames.map!fromStringz.array;

Basile B. <b2.temp gmx.com> writes:

On Monday, 9 July 2018 at 10:56:18 UTC, Andre Pany wrote:
 On Monday, 9 July 2018 at 10:38:54 UTC, Basile B. wrote:
 On Monday, 9 July 2018 at 10:33:03 UTC, Andre Pany wrote:
 Hi, no it's not correct i think, right translation would be

     extern(C) void GetParamNames(const char** paramNames, 
 size_t numParams);

 If you use the D array syntax you'll get into troubles because 
 of ABI i think.

 Baz.

 Thanks, it seems I also have to allocate the pointer before 
 with the numbers of numParams.
 In python the code looks s.th. like this

 self.output_names = (c_char_p * self.number_outputs)()

 Do you know that is the equivalent in D?

 Kind regards
 André

you don't need to allocate but to retrieve each string, do 
something like this:

     foreach(i; 0 .. numParams)
     {
         string p = fromStringz(paramNames + i)
     }

although i have a doubt for pointer arithmetic. Maybe it should 
be incremented by

     i * size_t.sizeof

since char.sizeof is 1. Maybe someone else will be more helpful 
here.

Baz.

Basile B. <b2.temp gmx.com> writes:

On Monday, 9 July 2018 at 11:10:01 UTC, Basile B. wrote:
 On Monday, 9 July 2018 at 10:56:18 UTC, Andre Pany wrote:
 On Monday, 9 July 2018 at 10:38:54 UTC, Basile B. wrote:
 On Monday, 9 July 2018 at 10:33:03 UTC, Andre Pany wrote:
 Hi, no it's not correct i think, right translation would be

     extern(C) void GetParamNames(const char** paramNames, 
 size_t numParams);

 If you use the D array syntax you'll get into troubles 
 because of ABI i think.

 Baz.

 Thanks, it seems I also have to allocate the pointer before 
 with the numbers of numParams.
 In python the code looks s.th. like this

 self.output_names = (c_char_p * self.number_outputs)()

 Do you know that is the equivalent in D?

 Kind regards
 André

 you don't need to allocate but to retrieve each string, do 
 something like this:

     foreach(i; 0 .. numParams)
     {
         string p = fromStringz(paramNames + i)
     }

 although i have a doubt for pointer arithmetic. Maybe it should 
 be incremented by

     i * size_t.sizeof

 since char.sizeof is 1. Maybe someone else will be more helpful 
 here.

 Baz.

Ok, i've read your other answers and it seems that you have a way 
to test so i think you'll figure it out yourself, but you don't 
need to alloc. Once the fromStringz verified to be good maybe 
dup/idup in case the C lib free the stuff but that's all.

Andre Pany <andre s-e-a-p.de> writes:

On Monday, 9 July 2018 at 11:39:46 UTC, Basile B. wrote:
 Ok, i've read your other answers and it seems that you have a 
 way to test so i think you'll figure it out yourself, but you 
 don't need to alloc. Once the fromStringz verified to be good 
 maybe dup/idup in case the C lib free the stuff but that's all.

Thanks a lot for your help.

Kind regards
André

Kagamin <spam here.lot> writes:

Correct signature:
extern(C) void GetParamNames(const(char)** paramNames, size_t 
numParams);
In C const applies only to the nearest member.

Andre Pany <andre s-e-a-p.de> writes:

On Monday, 9 July 2018 at 13:48:05 UTC, Kagamin wrote:
 Correct signature:
 extern(C) void GetParamNames(const(char)** paramNames, size_t 
 numParams);
 In C const applies only to the nearest member.

Thank you, that looks great.

Kind regards
Andre