title: Regex to validate numbers and forward slashes for date
body: <p>Hi I am trying to wright Regular Expression for date mm/dd/yyyy C#.
  I have this</p>
  <pre><code>^(0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])[- /.](19|20)\d\d$
  </code></pre>
  <p>But it doesn't work<br/>
  <img src="https://i.stack.imgur.com/ZuuPB.jpg" alt="enter image description here" /></p>
  <p>How to do so it will works with 3/1/2013 and with 03/01/2013</p>