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Thread: How to get poniter of array in Variant

  1. #1

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    How to get poniter of array in Variant

    Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)

    Private Sub Form_Load()

    ReDim a(1 To 10) As Long

    For w = 1 To 10
    a(w) = w
    Next

    Debug.Print VarPtr(a(1)), Q(a)



    ' Error solution: Q(a) <> VarPtr(a(1))
    ' Positive solution: how to let Q(a) solution Equal VarPtr(a(1))




    End Sub

    Function Q(ar) As Long


    Q = VarPtr(ar(1))

    ' purpose of the Problem is the following


    Redim ar_2(1 to 10) as long
    call CopyMemory ( varptr(ar_2(1)) , Q , 40)

    End Function
    Last edited by quickcccc; Sep 1st, 2012 at 12:32 PM.

  2. #2
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    Re: How to get poniter of array in Variant

    Can't really make heads or tails out of that. You have not dimmed anything and you are using a as an array but also using it like a number

  3. #3
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    Re: How to get poniter of array in Variant

    Why do you want the pointers in a Variant ? come to that why do you want the addresses in the first place?
    (EDIT: You understand that VarPtr stands for 'Variable Pointer' not 'Variant Pointer' don't you?)
    Code:
    Option Explicit
    
    Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
                (Destination As Any, _
                 Source As Any, _
                 ByVal Length As Long)
    
    Private Sub Command_Click()
    Dim intI As Integer
    Dim w(9) As Long
    Dim w_1(9) As Long
    Dim w_2(9) As Long
    For intI = 0 To 9
        '
        ' Put some values into the array w
        ' Put the pointer to each element into w_1 array
        ' (which is a bit absurd since once you know the address
        ' of the first element you just need to add 4 to get the next one)
        '
        w(intI) = CLng(intI)
        w_1(intI) = VarPtr(w(intI))
    Next intI
    For intI = 0 To 9
        '
        ' Output the Address of each element to the Immediate Window
        '
        Debug.Print Hex(w_1(intI))
    Next intI
    '
    ' This will copy the values of the w array into w_2
    ' using the Address of the first element obtained from VarPtr
    '
    CopyMemory w_2(0), ByVal w_1(0), (UBound(w_2) + 1) * 4
    For intI = 0 To 9
        Debug.Print w_2(intI)
    Next intI
    '
    ' This will also copy the values of the w array to w_2
    ' So it begs the Question -
    '           why do you want the Addresess of the elements?
    '
    CopyMemory w_2(0), w(0), (UBound(w_2) + 1) * 4
    For intI = 0 To 9
        Debug.Print w_2(intI)
    Next intI
    End Sub
    Last edited by Doogle; Sep 2nd, 2012 at 03:47 AM. Reason: Modified just about everything

  4. #4

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    Re: How to get poniter of array in Variant

    yes

    I understand that VarPtr stands for 'Variable Pointer'

    I attempt to find poniter as the following

    http://www.vbforums.com/showthread.p...73#post4228173

  5. #5

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    Re: How to get poniter of array in Variant

    Code:
    Public Sub AR_Copy_Long(store() As Long, store_lb, src() As Long, Optional lb, Optional ub)
       If IsMissing(lb) Then lb = LBound(src)
       If IsMissing(ub) Then ub = UBound(src)
       CopyMemory store(store_lb), src(lb), (ub - lb + 1) * Len(src(lb))
    End Sub 
    
    Public Sub AR_Copy_Sng(store() As Single, store_lb, src() As Long, Optional lb, Optional ub)
       If IsMissing(lb) Then lb = LBound(src)
       If IsMissing(ub) Then ub = UBound(src)
       CopyMemory store(store_lb), src(lb), (ub - lb + 1) * Len(src(lb))
    End Sub
    
    Public Sub AR_Copy_dbl(store() As Double, store_lb, src() As Long, Optional lb, Optional ub)
       If IsMissing(lb) Then lb = LBound(src)
       If IsMissing(ub) Then ub = UBound(src)
       CopyMemory store(store_lb), src(lb), (ub - lb + 1) * Len(src(lb))
    End Sub
    
    
    ' =======
    ' if I can get poniter of array in Variant ,
    ' I will have the onlyone sub
    
    Private Declare Sub CopyMemory2 Lib "kernel32" Alias "RtlMoveMemory" (ByVal Destination As Long, ByVal Source As Long, ByVal Length As Long)
    
    Public Sub AR_Copy_Any(store, store_lb, src, Optional lb, Optional ub)
       If IsMissing(lb) Then lb = LBound(src)
       If IsMissing(ub) Then ub = UBound(src)
    
       if (ub-lb) > (ubound(store) - store_lb)  then
           err.raise ....
           exit sub
       end if 
    
       src_ptr = ?   ' how to get poniter of array in Variant  ?
       store_ptr = ?
    
       CopyMemory2 store_ptr, src_ptr, (ub - lb + 1) * Len(src(lb))
    End Sub
    Last edited by quickcccc; Sep 2nd, 2012 at 07:07 AM.

  6. #6
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    Re: How to get poniter of array in Variant

    OK, but you still haven't said exactly what you're trying to achieve.

  7. #7

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    Re: How to get poniter of array in Variant

    VC++ 6.0 Variant define as the following

    Code:
        union {
    
            struct __tagVARIANT {
    
                VARTYPE vt;
    
                WORD    wReserved1;
    
                WORD    wReserved2;
    
                WORD    wReserved3;
    
                union {
    
                    LONG         lVal;         /* VT_I4                */
    
                    BYTE         bVal;         /* VT_UI1               */
    
                    SHORT        iVal;         /* VT_I2                */
    
                    FLOAT        fltVal;       /* VT_R4                */
    
                    DOUBLE       dblVal;       /* VT_R8                */
    
                    VARIANT_BOOL boolVal;      /* VT_BOOL              */
    
                    _VARIANT_BOOL bool;         /* (obsolete)           */
    
                    SCODE        scode;        /* VT_ERROR             */
    
                    CY           cyVal;        /* VT_CY                */
    
                    DATE         date;         /* VT_DATE              */
    
                    BSTR         bstrVal;      /* VT_BSTR              */
    
                    IUnknown *    punkVal;      /* VT_UNKNOWN           */
    
                    IDispatch *   pdispVal;     /* VT_DISPATCH          */
    
                    SAFEARRAY *   parray;       /* VT_ARRAY             */
    
                    BYTE *        pbVal;        /* VT_BYREF|VT_UI1      */
    
                    SHORT *       piVal;        /* VT_BYREF|VT_I2       */
    
                    LONG *       plVal;        /* VT_BYREF|VT_I4       */
    
                    FLOAT *       pfltVal;      /* VT_BYREF|VT_R4       */
    
                    DOUBLE *      pdblVal;      /* VT_BYREF|VT_R8       */
    
                    VARIANT_BOOL *pboolVal;     /* VT_BYREF|VT_BOOL     */
    
                    _VARIANT_BOOL *pbool;       /* (obsolete)           */
    
                    SCODE *       pscode;       /* VT_BYREF|VT_ERROR    */
    
                    CY *          pcyVal;       /* VT_BYREF|VT_CY       */
    
                    DATE *        pdate;        /* VT_BYREF|VT_DATE     */
    
                    BSTR *        pbstrVal;     /* VT_BYREF|VT_BSTR     */
    
                    IUnknown **   ppunkVal;     /* VT_BYREF|VT_UNKNOWN */
    
                    IDispatch ** ppdispVal;    /* VT_BYREF|VT_DISPATCH */
    
                    SAFEARRAY ** pparray;      /* VT_BYREF|VT_ARRAY    */
    
                    VARIANT *     pvarVal;      /* VT_BYREF|VT_VARIANT */
    
                    PVOID         byref;        /* Generic ByRef        */
    
                    CHAR         cVal;         /* VT_I1                */
    
                    USHORT       uiVal;        /* VT_UI2               */
    
                    ULONG        ulVal;        /* VT_UI4               */
    
                    INT          intVal;       /* VT_INT               */
    
                    UINT         uintVal;      /* VT_UINT              */
    
                    DECIMAL *     pdecVal;      /* VT_BYREF|VT_DECIMAL */
    
                    CHAR *        pcVal;        /* VT_BYREF|VT_I1       */
    
                    USHORT *      puiVal;       /* VT_BYREF|VT_UI2      */
    
                    ULONG *       pulVal;       /* VT_BYREF|VT_UI4      */
    
                    INT *         pintVal;      /* VT_BYREF|VT_INT      */
    
                    UINT *        puintVal;     /* VT_BYREF|VT_UINT     */
    
                    struct __tagBRECORD {
    
                        PVOID         pvRecord;
    
                        IRecordInfo * pRecInfo;
    
                    } __VARIANT_NAME_4;         /* VT_RECORD            */
    
                } __VARIANT_NAME_3;
    
            } __VARIANT_NAME_2;
    
     
    
            DECIMAL decVal;
    
        } __VARIANT_NAME_1;
    
    };

    try convert VC struct to VB Type ( but it exist error )

    Code:
    Private Type vt 
    vType As Integer
    p1 As Long
    p2 As Long
    p3 As Long
    p4 As Long
    p5 As Long
    p6 As Long
    p7 As Long
    p8 As Long
    p9 As Long
    End Type

  8. #8

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    Re: How to get poniter of array in Variant

    Private Type vt
    vType As integer
    p1 As Long
    p2 As Long
    p3 As long
    p4 As Long
    End Type

    Dim vt As vt

    b = CStr("123")
    Debug.Print VarType(b)
    CopyMemory2 vt, VarPtr(b) - 4, Len(vt)
    ' get vt.vType = 8 ( Just right = VB VarType( string var) )


    Private Type vt
    vType As integer
    p1 As Long
    p2 As Long
    p3 As long
    p4 As Long
    End Type

    b = CLng(123)
    Debug.Print VarType(b)
    CopyMemory2 vt, VarPtr(b) - 4, Len(vt)
    ' get vt.vType = 3 ( = VB VarType( long var ) )
    ' vt.p3 = 123

    Private Type vt
    vType As integer
    p1 As Long
    p2 As Long
    p3 As Single
    p4 As Long
    End Type


    b = CSng(123)
    Debug.Print VarType(b)
    CopyMemory2 vt, VarPtr(b) - 4, Len(vt)
    ' get vt.vType = 4 ( = VB VarType( single var ) )
    ' vt.p3 = 123
    Last edited by quickcccc; Sep 2nd, 2012 at 10:34 AM.

  9. #9
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    Re: How to get poniter of array in Variant

    I still don't have a clue what he's trying to achieve

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