Help with DLLStruct and DLLCall

[Leo1906]

Hello Guys,

once aggain I need your help on a DLL Topic

I need to pass arguments to my function via a structure, because I am limited to only one argument that can be passed.
But I don't think that thats so important.

So here's my approach:

C++ Code (just the important part):

extern "C"
{

    struct ParamStruct
    {
        const char* test1;
        const char* test2;
        const char* test3;
        int size;
    };

    int testFunc(struct ParamStruct * params)
    {   
        return params->size;
    }
}

And thats how I try to call the function using Autoit:

Local $struct = "struct;char shapefile[128];char output[128];char filename[128];int size;endstruct"
Local $tTest = DllStructCreate($struct)
DllStructSetData($tTest, "test1", "Bla")
DllStructSetData($tTest, "test2", "BlaBla")
DllStructSetData($tTest, "test3", "BlaBlaBla")
DllStructSetData($tTest, "size", 40)

$dll = DLLOpen("myDLL.dll")
$ret = DllCall($dll, "int:cdecl", "testFunc", "STRUCT*", DllStructGetPtr($tTest))
MsgBox(0, 0, $ret[0])

DllClose($dll)

Just for testing I want the function to just return the integer value in the struct.

But this aint working. I tested many things, but still I'm not able to get it running. I even don't know if the mistakes are in the C++ code or the Autoit code or both .. I'm not that skilled at C++ and also not that skilled at Autoit DLLCalls :-/

I would really appreciate some help!

Kind regards,
leo

Edited May 20, 2017 by Leo1906

[Leo1906]

Ok, I got it to work. Don't know what I changed but now it works ..

Another question: If I pass the Struct by ref, why can't Autoit get the changed values from the Struct?
Thats how it's done:

extern "C"
{

    struct ParamStruct
    {
        const char* test1;
        const char* test2;
        const char* test3;
        int size;
    };

    int testFunc(struct ParamStruct &params)
    {   
        params.size = 2;
        return params.size;
    }
}

#NoTrayIcon
Local $struct = "struct;char shapefile[128];char output[128];char filename[128];int size;endstruct"
Local $tTest = DllStructCreate($struct)
DllStructSetData($tTest, "test1", "bla")
DllStructSetData($tTest, "test2", "blabla")
DllStructSetData($tTest, "test3", "blablabla ")
DllStructSetData($tTest, "size", 40)


$dll = DLLOpen("Split_DLL.dll") ;<- open DLL
$ret = DllCall($dll, "int:cdecl", "testFunc", "STRUCT*", DllStructGetPtr($tTest))
MsgBox(0, 0, DllStructGetData($tTest, 4))

MsgBox(0, 0, $ret[0])
MsgBox(0, 0, DllStructGetData($tTest, 4))

DllClose($dll)

 

Edit: and another question. Can I use Strings in a Struct with Autoit? Can't find that dataformat in the helpfile regarding structs ..?

Edit2: Well the code seems not to work though .. as soon as I want to access the char's in the DLL Code Autoit crashes ..?

Edited May 20, 2017 by Leo1906

[Tekk]

ParamStruct is defining char pointers while the struct you create in Autoit is declaring char arrays.

Perhaps ParamStruct should look more like:
 

struct ParamStruct
    {
        char const test1[128];
        char const test2[128];
        char const test3[128];
        int size;
    };

 

[Leo1906]

Yeah you are right. Now it all works fine

Thanks a lot!