title: Extract the DateTime format from a given date string
body: <p>I was wondering if there was a way to extract the DateTime format from a given date string. In C#
  For example:</p>
  
  <pre><code>var dateString = "12/10/2018";
  var format = GetDateFormat(dateString);
  </code></pre>
  
  <p>and then the format will be like 'long date time' or something.</p>