Array Information

[Elroy]

For everything but BSTR arrays and a Variant containing an array, I just use the following:

Option Explicit
'
Public Declare Function ArrPtr Lib "msvbvm60" Alias "VarPtr" (a() As Any) As Long
Public Declare Function GetMem2 Lib "msvbvm60" (ByRef Source As Any, ByRef Dest As Any) As Long ' Always ignore the returned value, it's useless.
Public Declare Function GetMem4 Lib "msvbvm60" (ByRef Source As Any, ByRef Dest As Any) As Long ' Always ignore the returned value, it's useless.
'

Public Function ArrayDims(pArray As Long) As Integer
    ' Won't work with BSTR arrays nor a Variant containing an array.
    ' Works with arrays of variants, of all other intrinsic types, of objects, and of fixed length strings.
    ' Example:  Debug.Print ArrayDims(ArrPtr(SomeArray()))
    ' Returns 0 if not dimensioned.
    '
    Dim pSA As Long
    If pArray = 0& Then Exit Function
    GetMem4 ByVal pArray, pSA                                       ' De-reference.
    If pSA = 0& Then Exit Function                                  ' Dynamic undimensioned array.
    GetMem2 ByVal pSA, ArrayDims
End Function

On BSTR arrays and a Variant containing an array, different approaches must be taken.

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Here's some test code that can be thrown into a Form1:

Option Explicit

Private Sub Form_Load()
    Dim a() As Long

    Debug.Print "a()", ArrayDims(ArrPtr(a))
    ReDim a(1, 2, 3, 4, 5)
    Debug.Print "a()", ArrayDims(ArrPtr(a))

End Sub