[RESOLVED] [Excel 2003 VBA]: CopyMemory with Objects

[alex_read]

Hi everyone,

Can someone lend me a hand & tell me what I'm doing wrong here please?? I'm trying to use the CopyMemory API call in Excel, but without any luck. Could be the object length perhaps? (Len & LenB don't seem to want to work with an object type here)...

'In a module...
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
(pDst As Any, pSrc As Any, ByVal ByteLen As Long)

Sub testit()
    Dim classInstance1 As Class1
    Dim classInstance2 As Class1
    
    Set classInstance1 = New Class1
    classInstance1.AStringValue = "hello world"
    
    CopyMemory ObjPtr(classInstance2), ObjPtr(classInstance1), 4
    classInstance1.AStringValue = "REPLACED"
    MsgBox classInstance1.AStringValue & "  --  " & classInstance2.AStringValue
End Sub

'In a class (Class1)...
Private m_stringValue As String

Public Property Get AStringValue() As String
    AStringValue = m_stringValue
End Property

Public Property Let AStringValue(ByVal newString As String)
    m_stringValue = newString
End Property

[westconn1]

' Copy the first 1000 elements of array a() to b()
' both arrays must be of the same type, and can't be objects
' nor variable-length strings
CopyMemory b(0), a(0), 1000 * Len(a(0))

from http://www.devx.com/vb2themax/Tip/18519

[alex_read]

Hi guys, and thanks for the responses (the earlier one which someone deleted too). Seems the 1st argument should have been an object & not a pointer was the main reason here. All hunky-dory now! This code works if anyone finds it useful for the future...

Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
(pDst As Any, pSrc As Any, ByVal ByteLen As Long)

Sub testit()
    Dim classInstance1 As Class1
    Dim classInstance2 As Object
    
    Set classInstance1 = New Class1
    classInstance1.AStringValue = "hello world"

    CopyMemory classInstance2, ObjPtr(classInstance1), 4
    
    MsgBox "classInstance1.AStringValue: " & classInstance1.AStringValue
    MsgBox "classInstance2.AStringValue: " & classInstance2.AStringValue

    CopyMemory classInstance1, CLng(0), 4
    Set classInstance1 = Nothing

    MsgBox "classInstance2.AStringValue: " & classInstance2.AStringValue
    
    CopyMemory classInstance2, CLng(0), 4
    Set classInstance2 = Nothing
End Sub