title: Filter raise an exception
body: <pre><code>public List&lt;Video&gt; filtra_data(string date)
              {
                  List&lt;Video&gt; lista_filtrata = new List&lt;Video&gt;();
                  for (int i = 0; i &lt; listavideo.Count; i++)
                  {
                      if (listavideo[i].Data.Contains(date) == true)
                          lista_filtrata.Add(listavideo[i]);
                  }
                  return lista_filtrata;
              }
  </code></pre>
  
  <p>i made this method to filter a list of movies using the date as parameter but when, on the form, i put the input in the textbox and i press the button it raises an exception on the for: object reference not set to an instance of an object, any ideas? thank you everyone</p>