Re: varptr to structs returns bad pointer value

[vuott@xxxxxxxxxxxx]

Hello,
...try:


Private Extern myFunction(data As Pointer) In "mylib"

Public Struct myStruct
    result As Long
    msg As String
End Struct

Private myData As Struct Mystruct

Public Sub doit2()
  
  myFunction(VarPtr(myData))
  
End






27 feb 2025, 21:13 da brian@xxxxxxxxxxxxxxxx:

> I am not sure if this is a bug or not
>
> When passing structures to external c functions varptr fails to produce the correct pointer...
> to the data of the structure. I think maybe I don't understand the difference, but it would seem they should
> produce the same result.
>
> extern myFunction(data as pointer) use "mylib"
> public dataSet as pointer
> public struct myStruct
>     result as long
>     msg as string
> end struct
> public mydata as mystruct
>
> this works as expected
>
> public sub doit()
>   dataSet = alloc(sizeof(mystruct))
>   mydata = dataSet
>   myFunction(dataSet)  ' this works
> end sub
>
> this fails
>
> public sub doit2()
>   mydata = new myStruct
>   dataSet = varptr(myData)
>   myFunction(dataSet)  ' this fails invalid pointer provided
> end sub
>
> -- 
> ~~~~ Brian
>