Question

I can’t get to pass structure as argument through subs/functions in different files of single vbnet project like I use to in earlier MS basic versions.
Here is short example of situation:

Module1.vb

Imports System.IO

Structure mymultitry
     Dim index As Integer
    <VBFixedString(6)> Dim name As String
    Dim weight As Double
End Structure

Module Module1
Public mysetupfile = "mysetup.dat"

Public Sub rwfile(ByVal rw As Integer, ByVal myrecord As Integer, ByVal mmt As mymultitry)

'EDIT: Thanks to SteveDog - proper line should be:
'Public Sub rwfile(ByVal rw As Integer, ByVal myrecord As Integer, ByRef mmt As mymultitry)

    Dim fnum As Integer
    fnum = FreeFile()
    FileOpen(fnum, mysetupfile, OpenMode.Random, OpenAccess.ReadWrite, OpenShare.Shared, Len(mmt))
    If rw Then
        FilePut(fnum, mmt, myrecord)
    Else
        FileGet(fnum, mmt, myrecord)
    End If
    FileClose(fnum)
End Sub

End Module

Form1.vb

Public Class Form1
Dim mmt As mymultitry
Dim mmt1 As mymultitry

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    With mmt
        .index = 4
        .name = "Helga"
        .weight = 128.1445
    End With
    rwfile(1, 1, mmt)  'write

    rwfile(0, 1, mmt1) 'read

    'all zero here !?!
    Debug.Print(mmt1.index)
    Debug.Print(mmt1.name)
    Debug.Print(mmt1.weight)

End Sub
End Class

File “mysetup.dat” is reachable and data is saved correctly what I can see with HxD.
But read part seem’s to not work as expected.

Please any help on reliable passing structure as argument without too much public elements based on upper example.

Answer 1

I strongly suggest you rewrite your code to use the new .NET IO methods in the System.IO.File class, but, that aside, I think your problem with your existing code is that you need to change your mmt argument from ByVal to ByRef.