DotNetZip why is the last line always truncated

Question

every zip file has a truncated last row. I output the row tot he console and it's not truncated, why would the last line of the compressed file be truncated?

using (SqlConnection conn = new SqlConnection(ConfigurationManager.AppSettings["connstring"]))
        {
          conn.Open();
          using (SqlCommand cmd = new SqlCommand())
          {
            cmd.Connection = conn;
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.CommandText = "final_out";
            cmd.Parameters.Add("@jobid", SqlDbType.VarChar).Value = jobid;
            cmd.Parameters.Add("@filename", SqlDbType.VarChar).Value = filename;
            using (SqlDataReader rdr = cmd.ExecuteReader())
            {
              using (MemoryStream ms = new MemoryStream())
              {
                using (StreamWriter sw = new StreamWriter(ms))
                {
                  while (rdr.Read())
                  {
                    string nextval = rdr[0].ToString();
                    sw.WriteLine(nextval);
                    Console.WriteLine(nextval);
                  }
                  ms.Flush();
                  ms.Position = 0;
                  using (ZipFile zf = new ZipFile(Path.Combine(Path.GetDirectoryName(finalPath), Path.GetFileNameWithoutExtension(finalPath) + ".zip")))
                  {
                    zf.AddEntry(Path.GetFileName(finalPath), ms);
                    zf.Save();
                  }
                }
              }
            }
          }
        }

Answer 1

Because you're not flushing the StreamWriter.

You're flushing the MemoryStream, which is a no-op.

The StreamWriter class keeps a buffer internally, which you have not flushed, so the last few lines and/or characters will still be sitting in this buffer. If you click the link and look at the documentation you can see that the constructor documentation says such things as:

Initializes a new instance of the StreamWriter class for the specified stream by using UTF-8 encoding and the default buffer size.

(my emphasis)

---

Replace this:

ms.Flush();

with this:

sw.Flush();

Here's a simple LINQPad program that demonstrates:

void Main()
{
    using (var ms = new MemoryStream())
    using (var sw = new StreamWriter(ms, Encoding.UTF8))
    {
        for (int index = 1; index <= 200; index++)
            sw.WriteLine("Line #" + index);

        ms.Flush();
        ms.Position = 0;

        Encoding.UTF8.GetString(ms.ToArray()).Dump();
    }
}

Output:

Line #1
Line #2
...
Line #196

(missing is line 197 through 200.)

After replacing ms.Flush(); with sw.Flush(); and running again the missing lines are present.