CanRead Property

In This Topic

Gets a value indicating whether the SQLiteBlob stream can be read.

Syntax

Visual Basic
C#

'Declaration
 
Public Overrides ReadOnly Property CanRead As Boolean

public override bool CanRead {get;}

Property Value

true if the SQLiteBlob stream supports reading; false if a SQLiteBlob is closed, disposed, or Null.

Remarks

Use CanRead property to determine whether SQLiteBlob object supports reading. SQLiteBlob can not be read from if it has Null value.

Example

csharp

void ReverseBlob()
{
  byte[] byteArray = { (byte)'A', (byte)'B', (byte)'C' };
  SQLiteBlob blobFrom = new SQLiteBlob(byteArray);
  //blobFrom.ToString() = "ABC"

  SQLiteBlob blobTo = new SQLiteBlob();
  ........
  //reverse SQLiteBlob
  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 SQLiteBlob(byteArray)
  ' blobFrom.ToString() = "ABC"

  Dim blobTo As New SQLiteBlob
  ......
  ' reverse SQLiteBlob
  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

SQLiteBlob Class
SQLiteBlob Members

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