title: Create a blank vector of dates
body: <p>How can I define a blank vector which can handle dates?</p>
  
  <p>For example:</p>
  
  <pre><code># this doesn't work ... produces error message
  test_vct &lt;- vector(mode = "Date")
  
  # this works but
  test_vct &lt;- vector(mode = "double")
  dte_current_upper &lt;- as.Date("2014-12-31")
  
  
  test_vct &lt;- c(test_vct, as.Date("2014-12-31"))
  # this displays as 16435
  test_vct
  
  # a vector of dates is possible but how to define a blank vector ?
  vct_dates &lt;- c(as.Date("2014-12-31"), as.Date("2013-12-31"))
  class(vct_dates)
  </code></pre>