CanSeek Property

In This Topic

Gets a value indicating whether forward and backward seek operations can be performed.

Syntax

Visual Basic
C#

'Declaration
 
Public Overrides ReadOnly Property CanSeek As Boolean

public override bool CanSeek {get;}

Property Value

true if the OracleLob stream supports seeking; false if a OracleLob is closed, disposed, or Null.

Remarks

Use this property to find out if a OracleLob supports Seek operation. OracleLob does not support seeking if it has Null value as well as if it has been disposed or closed.

Example

csharp

static void ReverseBlob() 
{ 
        byte[] byteArray = { (byte)'A', (byte)'B', (byte)'C' }; 
        OracleLob blobFrom = new OracleLob(OracleDbType.Blob);
        blobFrom.Write(byteArray, 0, byteArray.Length);
        //blobFrom.ToString() = "ABC" 

        OracleLob blobTo = new OracleLob(OracleDbType.Blob); 
        ........
        //reverse OracleLob 
        if (blobFrom.CanSeek && blobFrom.CanRead && blobTo.CanWrite) 
                for (blobFrom.Seek(-1, System.IO.SeekOrigin.End); ;blobFrom.Position -= 2) 
                { 
                        blobTo.WriteByte((byte)blobFrom.ReadByte()); 
                        if (blobFrom.Position == 1) break; 
                } 
        //blobTo.ToString() = "CBA"; 
}

Visual Basic

Private Sub ReverseBlob()
        Dim byteArray As Byte() = New Byte() {AscW("A"c), AscW("B"c), AscW("C"c)}
        Dim blobFrom As New OracleLob(OracleDbType.Blob)
        blobFrom.Write(byteArray, 0, byteArray.Length)
        ' blobFrom.ToString() = "ABC"

        Dim blobTo As New OracleLob(OracleDbType.Blob)
        ........
        ' reverse OracleLob
        If ((blobFrom.CanSeek AndAlso blobFrom.CanRead) AndAlso blobTo.CanWrite) Then
                blobFrom.Seek(CLng(-1), System.IO.SeekOrigin.End)
                Do While True
                        blobTo.WriteByte(CByte(blobFrom.ReadByte))
                        If (blobFrom.Position = 1) Then
                                Return
                        End If
                        blobFrom.Position = blobFrom.Position - 2
                Loop
        End If
        ' blobTo.ToString() = "CBA";
End Sub

Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

OracleLob Class
OracleLob Members

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