title: Converting Datetime and TImespan to String
body: <pre><code>        public Nullable&lt;DateTime&gt; SessionStartDT { get; set; }
          public TimeSpan SessionStartTM { get; set; }
          public Nullable&lt;DateTime&gt; SessionEndDT { get; set; }
          public TimeSpan SessionEndTM { get; set; }
          public string Start
          {
              get
              {
                  return SessionStartDT?.ToString("yyyy-MM-dd") + "T" + SessionStartTM.ToString();
              }
          }
          public string End
          {
              get
              {
                  return SessionEndDT?.ToString("yyyy-MM-dd") + "T" + SessionEndTM.ToString();
              }
          }
  </code></pre>
  
  <p>I am getting a compilation error on my return statements. Also I am getting "feature null propagation operator is not available in c# 5". How can I change this ?</p>