title: Cannot implicitly convert type string to to StreamWriter
body: <p>I'm trying to split a file in to 10 pieces. This is the way I think I can do it but I'm getting the error mentioned in the title. Is there an easy fix to this problem?</p>
  
  <pre><code>StreamWriter a = new StreamWriter(new FileStream(@"C:\work\missing" + num + ".txt");
  
  using (var r = new StreamReader(readMissing))
                  {
                      var rr = r.ReadLine();
                      while (rr != null)
                      {
                          a.WriteLine(rr);
                          count++;
  
  
                          if (count == 36139)
                          {
                              iNum = Int32.Parse(num);
                              iNum++;
                              num = iNum.ToString();
                              a = (@"C:\work\missing" + num + ".txt");  //problem line
  
                              count = 0;
                          }
                          rr = r.ReadLine();
  
  
                      }
                      a.Close();
                  }
  </code></pre>