Question

I am looking at some old VB6 code. I am new to VB and I come from a C/Java background, so I don’t understand some of the assignment statements. Here is one example –

     Private Type UGH
       Rsp(3) As Byte
       ProgramId(7) As Byte
       RID(7) As Byte
       TID(3) As Byte
       FL(39) As Byte
    End Type
    Private UHeader As UGH

Later, the assignment takes place as follows-

    With UHeader
    StringToByteArray UHeader.ProgramId(), "ABCDPQRS"

My question is, why is the parenthesis used after ProgramId in the above assignment? To me it seems like a function call, but it obviously is not a function call. Then what is it?

Answer 1

Well it is not actually needed. Calling the same line without the parenthesis will do exactly the same thing. The reason it is allowed is because it is a byte array.

Maybe rewriting the line like this will make it more readable:

call StringToByteArray(UHeader.ProgramId(), "ABCDPQRS")

But this is also valid:

call StringToByteArray(UHeader.ProgramId, "ABCDPQRS")

It would probably make more sense to you if the StringToByteArray method was a function instead of a subroutine:

Private Function StringToByteArray(ByVal strValue As String) As Byte()
    'conversion code left out
End Function

Then you can call it like this:

UHeader.ProgramId() = StringToByteArray("ABCDPQRS")

or this:

UHeader.ProgramId = StringToByteArray("ABCDPQRS")