Convert C++ Union Struct to VB6

Question

I have this struct in my C++ app:

struct textField
{
        //0
        union nameField
        {
                void* ptr;
                char cstring[16];
        } text;
        //16
        uint8_t textLength;
        //17
        char unknown1[3];
        //20
        uint8_t fieldType;
        //21
        char unknown2[3];
        //24
        uint32_t unknown3;
        //28
};

And I know that in VB6, it will look something like this:

Private Type textField        ' 0
    cstring(0 To 15) As Byte  ' 16
    textLength       As Byte  ' 17
    unknown1(0 To 2) As Byte  ' 20
    fieldType        As Byte  ' 21
    unknown2(0 To 2) As Byte  ' 24
    unknown3         As Long  ' 28
End Type

But what about the union in the struct? How can it be accomplished?

Answer 1

The easiest way is to use the variant type - this can contain any other type.

Note that there probably is no direct mapping of void * into VB so you will need to study how the union is used rather than just a quick conversion.

Answer 2

Use the LSET command.

It's not declared in line with the struct, but rather thereafter upon declaring an instance of the object.

Example :

Private Type MyType1
    x as Integer
    y as Integer
    z as Integer
    w as Integer
End Type

Private Type MyType2
    a as Long
    b as Long
End Type

Private Sub Form_Load()
    Dim t1 as MyType1
    Dim t2 as MyType2
    t1.x = 0
    t1.y = 0
    t1.z = -1
    t1.w = -1

    LSet t2 = t1
    ....

This has the same effect as an unnamed union between the two types.