How to move data from one buffer to another

See more:

C#

hi,
Actually I am working on streamer .the data is coming from fx3 board
that data is storing in buffer from that buffer I am copying to another buffer and then saving to pc . after reaching limit of the buffer size it is throwing an exception .so I want to do this for continuously save data without stoping the streamer . I want to clear the buffer after copied the data from that buffer to another buffer. the functions which I tried is attached below .I hope some one will help to sort out of this problem

What I have tried:

byte[] temp=new byte[100*1024*1024];

if (Save == true)   //Check if save Button is marked
              {



                          byte[] temp1 = new byte[Offset];

                          Buffer.BlockCopy(temp, 0, temp1, 0, Offset);  // copy the contents received on  temp[] to temp1[]
                          string res = string.Join("", temp1);
                                                          // Put all the data streamed to a single string
                          string file_name = "C:\\user\\mady\\desktop\\myData.txt";    // Write the string to mady.txt
                          System.IO.StreamWriter objWriter;
                          objWriter = new System.IO.StreamWriter(file_name);
                          objWriter.WriteLine(res);

                          objWriter.Close();




                  }