Parsing OLEVARIANT in VB

[daliaessam]

Can anyone please tell me how to copy the safearray returned in Variant as OLEVARIANT from the IOLECOMMANDTarget.Exec, here is what I did and it works fine except only one step explained in the code below:

I am using this:

Dim varIn As Variant
Dim varOut As Variant
 
'Here I execute the command to get block formats and it returns an OLE Variant with a pointer to safearray
 
IOLECoammndTarget.Exec IDM_GETBLOCKFMTS, OLECMDEXECOPT_DONTPROMPTUSER, varIn, varOut

Here is my sub to parse the OLE Variant array returned which points to safearray.

Public Sub ParseOleVariantArray(varArray As Variant, Elements() As String)
'
' Given a stream of bytes that represent a Microsoft SafeArray, wade through
'the garbage and get the actual data found in the array.  Write the data to disk.
 
'      SafeArray looks like
'typedef struct FARSTRUCT tagSAFEARRAY {
'    unsigned short cDims;           // Count of dimensions in this array.
'    unsigned short fFeatures;     // Flags used by the SafeArray
'                                    // routines documented below.
'    unsigned long cbElements; // Size of an element of the array.
'                               // Does not include size of
'                               // pointed-to data.
'    unsigned long cLocks;  // Number of times the array has been
'    void HUGEP* pvData;   // Pointer to the data.
'    SAFEARRAYBOUND rgsabound[1]; // One bound for each dimension.
'} SAFEARRAY;
'SAFEARRAYBOUND is a two-longword structure, the first 32 bits hold the # of
'elements in the array, the second 32 bits hold the lower bound of the array.
'There is one structure for every dimension of the array.
'http://groups-beta.google.com/group/microsoft.public.vc.vcce/browse_thread/thread/7f2bfbdb6ef17e98/a90475b71136f83b?q=OleSafeArray+visual+basic&rnum=2&hl=en#a90475b71136f83b
 
'Public Type OLEVARIANT
'    vt As Integer 'variable type
'    wReserved1 As Integer
'    wReserved2 As Integer
'    wReserved3 As Integer
'    lVal As Integer
'    iVal As Integer
'    bstrVal As Long
'    pUnkVal As Long
'    pArray As Long
'    pvRecord As Long
'    pRecInfo As Long
'End Type
 
    Dim pArray As Long
    Dim ppArray As Long
    Dim ppVarStruct As Long
    
    Dim intDims As Integer
    Dim intFeatures As Integer
    Dim lElements As Long
    Dim lLocks As Long
    Dim lDataPtr As Long
    Dim lElementCount As Long
    Dim lLbound As Long
    
    Dim lOffset As Long
    Dim lDataTemp As Long
    Dim i As Long
    Dim vType As Long
    '----------------------------------------------------------------
    ' First get a pointer to the variant.
    ppVarStruct = VarPtr(varArray)
    
    'Get the variable type
    'CopyMemory vType, ByVal ppVarStruct, 2
    'Debug.Print "vType: " & vType
 
    ' Get the pointer to the data *inside* the variant.  The VARTYPE is 2 bytes,
    ' and each of the three reserved words are also 2 bytes, giving 8 bytes total.
    '
    CopyMemory ppArray, ByVal ppVarStruct + 8, 4
    
    ' Now parse the SafeArray structure.  The most important parts to me are the
    ' Number of elements and the pointer to the actual data.
    '
    lOffset = 0
    CopyMemory intDims, ByVal (ppArray + lOffset), ByVal Len(intDims)
 
    lOffset = lOffset + Len(intDims)
    CopyMemory intFeatures, ByVal (ppArray + lOffset), ByVal Len(intFeatures)
 
    lOffset = lOffset + Len(intFeatures)
    CopyMemory lElements, ByVal (ppArray + lOffset), ByVal Len(lElements)
 
    lOffset = lOffset + Len(lElements)
    CopyMemory lLocks, ByVal (ppArray + lOffset), ByVal Len(lLocks)
 
    lOffset = lOffset + Len(lLocks)
    CopyMemory lDataPtr, ByVal (ppArray + lOffset), ByVal Len(lDataPtr)
 
    lOffset = lOffset + Len(lDataPtr)
    CopyMemory lElementCount, ByVal (ppArray + lOffset), ByVal Len(lElementCount)
 
    lOffset = lOffset + Len(lElementCount)
    CopyMemory lLbound, ByVal (ppArray + lOffset), ByVal Len(lLbound)
    '===============================================
    Dim strElement As String
    
    If lElementCount > 0 Then
        ReDim Elements(lElementCount)
        For i = 0 To (lElementCount - 1)
                'Copy the array string element pointer to lDataTemp
                CopyMemory lDataTemp, ByVal lDataPtr, ByVal lElements
                
                'strElement = Space(100)
                
'************************************************
'************************************************
'************************************************
'Here is my problem, if I comment these lines, everything works fine always, If not, after few function calls I get can not write or read memory errors and the program exits. I guess I am not copying the safearray string variables correctly from the Variantto the returned array, please help here.
 
                'Copy the array string element to the variable strElement
                CopyMemory strElement, lDataTemp, ByVal lElements
 
                Elements(i) = StrConv(strElement, vbFromUnicode)
 
                'CopyMemory Elements(i), lDataTemp, ByVal lElements
'************************************************
'************************************************
'************************************************                
 
                'Next array element pointer
                lDataPtr = lDataPtr + lElements
                strElement = ""
        Next i
    End If
    
    'I tried to free the safearray, it works
    'Debug.Print "SafeArrayDestroyData: " & SafeArrayDestroyData(ppArray)
    'Debug.Print "SafeArrayDestroy: " & SafeArrayDestroy(ppArray)
End Sub

Thank you

[daliaessam]

I found this but it did not help in my case as this is OleVariant which I do not know if it is the same as VB Variant or not:

http://support.microsoft.com/kb/q167668/

How to pass a SafeArray of strings in a VARIANT* between Visual C++ and Visual Basic 6.0


Now you can build and test the automation server. After you build the server, run it as a stand-alone to register it. Run Visual Basic 6.0 and create a new Visual Basic 6.0 project. Place a button on the form and modify the handler to match the code below:

Private Sub Command1_Click()
Dim o As Object
Dim v As Variant
ReDim v(50) As String
Dim SortTime As Long

Set o = CreateObject("StrArray.Document")

upperbound = 1
lowerbound = 100
For n = 0 To 50
v(n) = "Entry " & Int((upperbound-lowerbound+1)*Rnd+lowerbound)
Next n

SortTime = o.Sort(v)
MsgBox ("Done")
End Sub



The key to getting this syntax to work in Visual Basic 6.0 is to first Dim the array variable as a variant, and then ReDim it so that it becomes a variant containing an array of strings. Now you are ready to test the server. Set break points in the Visual Basic 6.0 code before and after the call to Sort. Run the Visual Basic 6.0 application, click Command1 and use the watch window to check the values for v.