Buffer

Sets or returns the contents of a control’s current record buffer. The record buffer is the raw record data retrieved by PSQL.

object.Buffer(short alignment)

The Buffer property syntax has these parts:


Part	Description
object	Required. The name of the VAccess object represents an object expression that evaluates to an object in the Applies To list.
alignment	Required. Specifies byte alignment of data. The accepted values for alignment are 1, 2, 4, 8, and 16 bytes.

Data is read from and written to the current record buffer. On a read operation, this property returns an OLE Variant containing a byte array representation of the current record buffer. On a write operation, it takes an OLE Variant which contains a byte array to be written to the current record buffer. Changes made to this property are not saved in the Btrieve file until a successful Update or Insert method is invoked.

The buffer that is returned is the single record buffer only; it will not contain the contents of the status buffer after a Stat call, nor will it contain an extended operations record buffer after an extended operations call. This information is available through other properties and methods (see Stat, RowColumnValue, and RowPosition). The Clear method will clear this buffer.

Certain programming environments allow or require specific byte alignment for structured variables. The alignment parameter enables you to specify the byte alignment to be used for individual fields within the record.

This property is not available at design time.

Public Type SAFEARRAYBOUNDS

cElements As Long

lLbound As Long

Public Type SAFEARRAY

cDims As Integer

fFeatures As Integer

cbElements As Long

Bounds(0) As SAFEARRAYBOUNDS

Public Type Buffer

msa_desc As String * 34

population As Long

prev_population As Long

Declare Sub CopyMemory Lib "KERNEL32" Alias _ "RtlMoveMemory" (pDest As Any, pSrc As Any, ByVal _ ByteLen As Long)

Declare Function VarPtrArray Lib "msvbvm50.dll" _ Alias "VarPtr" (Ptr() As Any) As Long

Public Sub ReadData()

Dim i as integer

Dim dataArray() as Buffer

Dim byteArray() as Byte

VAccess1.GetFirst

Redim dataArray(VAccess1.TotalRecords)

For i = 0 to VAccess1.TotalRecords-1

ByteArray = VAccess1.Buffer(4)

DataArray(i) = GetBuffer(byteArray)

VAccess1.GetNext

Public Function GetBuffer(bufferArray() As Byte) _
as Buffer

Dim status As Integer

Dim saPtr As Long

Dim saStruct As SAFEARRAY

Dim record as Buffer

'get the address of safearray structure

CopyMemory saPtr, ByVal VarPtrArray(bufferArray),_ 4

'copy the safearray structure

CopyMemory saStruct, ByVal saPtr, Len(saStruct)

'copy the data array into our structure

CopyMemory record, ByVal saStruct.pvData, BufferSize(saStruct)

GetBuffer = record

Affected by: Clear, GetDirect, GetEqual, GetGreaterOrEqual, GetLessOrEqual, GetFirst, GetPrevious, GetNext, GetLast, StepFirst, StepPrevious, StepNext, StepLast, Percentage.