Reading pdf File

FileStream ReadPdf = new FileStream(Server.MapPath("test.pdf"), FileMode.Open);
long FileSize;
FileSize = ReadPdf.Length;
byte[] Buffer = new byte[(int)FileSize];
ReadPdf.Read(Buffer, 0, (int)ReadPdf.Length);
for (int i = 0; i < buffer.count ; i++)
TextBox1.Text = TextBox1.Text + (char)Buffer[i];
ReadPdf.Close();