Question

I have interesting situation with passing two-dimensional array through functions.
Array is declared at form’s level scope:
I try to rewrite a part of my code from VB6 where I have workable example.

Dim myArray(,) As Double

Then I get a sub where array is redimed and filled according to data, something like this, symbolic situation:

Public Sub mySub(ByVal myArray(,) As Double)

    Dim temparray() As Double = {3, 5, 7, 9}
    For a As Double = 0 temparray.length - 1
         ReDim Preserve myarray(2, temparray(a))
    Next a

    myArray(1, 5) = 3.14
    ... etc...
End Sub

And finally, I would like to fill and read data in array from other sub:

mySub(myArray)
Debug.Print(myArray(1, 5))

And here I get error message:

Object reference not set to an instance of an object.

Data in mySub is filled properly but I can’t see this data in calling sub.
What do I do wrong and how can I get this scenario working?

Answer 1

You can solve it by doing this:

Public Sub mySub(ByRef myArray(,) As Double)
    '...
End Sub

You need to reference the variable in order to have the changes outside the Sub.