title: How to insert a space into a string, between every 4 characters?
body: <p>The string displays value as:</p>
  
  <pre class="lang-none prettyprint-override"><code>123456789012
  </code></pre>
  
  <p>I need it like:</p>
  
  <pre class="lang-none prettyprint-override"><code>1234 5678 9012
  </code></pre>
  
  <p>There should be space between every 4 characters in this string. How do I do that?</p>
  
  <pre><code>displaynum_lbl.Text = Regex.Replace(printClass.mynumber.ToString(), ".{4}", "$0");
  </code></pre>