將數據寫入文本文件中的特定位置

Question

我需要在第30個位置的現有文本文件中寫入數據。我正在使用尋找，但不工作。使用下面的代碼。使用開始位置爲30.

Public Sub WriteToFile(ByVal data As DataTable, ByVal FileName As String, ByVal FieldLength As String, ByVal StartPosition As String) 
     Dim sbColumnData As New StringBuilder 

     Using writer = New StreamWriter(Directory.GetCurrentDirectory() + "\test.txt") 
      For Each oRecord In data.Rows 
       sbColumnData.Clear() 
       If oRecord(0).ToString().Length < FieldLength Then 
        sbColumnData.Append(oRecord(0).ToString().PadRight(FieldLength)) 
       ElseIf oRecord(0).ToString().Length = FieldLength Then 
        sbColumnData.Append(oRecord.ToString()) 
       Else 
        sbColumnData.Append(oRecord.ToString().Substring(0, FieldLength)) 
       End If 
       writer.Seek(0, StartPosition) 

       writer.WriteLine(sbColumnData) 
       writer.Flush() 
      Next 

     End Using 

    End Sub 

Answer 1

您的語法錯誤。嘗試：

writer.Seek(StartPosition, SeekOrigin.Begin) 
writer.Write(sbColumnData, 0, sbColumnData.Length); 

https://msdn.microsoft.com/en-us/library/system.io.filestream.seek%28v=vs.110%29.aspx?f=255&MSPPError=-2147217396