VB.net Passing an Unmanaged Dll Structure

Question

I am porting some VB6 code to VB.net, the code contains a structure containing 1d arrays, 2d arrays and several other variables.

The general structure diagram of Vb.net is under

Public Structure Test

    Dim a As Single
    Dim b As Single
    Dim c As Single
    <VBFixedArray(2)> Dim arr1() As Single
    <VBFixedArray(2, 2)> Dim mdarr1(,) As Single
    <VBFixedArray(4)> Dim arr2() As Byte
    <VBFixedArray(4)> Dim arr3() As Short
    <VBFixedArray(3, 2)> Dim mdarr2(,) As Integer

    Dim d As Integer
    Dim e As Decimal

End Structure

DLL call is declared as

Public Declare Sub getState Lib "val.dll" (ByRef state As Test)

Elsewhere on this site, I realized that we must “marshal” the structure so that it can be compatible with the unmanaged code that is going to accept it.

However, I still get errors while executing the code, I don't know how to use the class System.Runtime.InteropServices.Marshal.

What would be the proper way to pass this structure to the dll?

EDIT:

Original data type VB6

Public Type Test

    a As Single
    b As Single
    c As Single
    arr1(0 To 2) As Single
    mdarr1(0 To 2, 0 To 2) As Single
    arr2(0 To 4) As Byte
    arr3(0 To 4) As Integer
    mdarr2(0 To 3, 0 To 2) As Long

    d As Long
    e As Currency

End Type

Answer 1

getState val.dll? C ++, , P/Invoke Assistant VB.Net.

... (, , VB6!)

• getState, . state.arr1 = {0.0, 0.0} ..
• Decimal e . VB6 , , Currency, Decimal , . VB.Net , . , attribute, ...

:

 Imports System.Runtime  
 Public Structure Test  
   ''blah blah

   <InteropServices.MarshalAs(InteropServices.UnmanagedType.Currency)> _  
   Dim e As Decimal  

   ''blah blah