title: RegEx to match a specific format: 4 digits and 6 characters in a string
body: <p>I'm trying to design a RegEx in C# to match 4 digits and 6 characters in a string.</p>
  
  <pre><code> string str = "Hello World! ABCD112233 fsdf sdfsdf 234324 fdsfds 4234 efwedf34ref dfsdf34f34f";
  </code></pre>
  
  <p>that matches only ABCD112233 in the above string.</p>
  
  <pre><code>Regex regex = new Regex("^[A-Za-z]{4}[0-9]{6}$", RegexOptions.Multiline);
  </code></pre>
  
  <p>How do I solve this problem?</p>