title: Perl Regular Expressions to match a MD5 Hash?
body: <p>Recently programming in PHP, I thought I had a working Perl regular expression but when I checked it against what I wanted, it didn't work.</p>
  
  <p>What is the right expression to check if something is a MD5 has (32 digit hexadecimal of a-z and 0-9).</p>
  
  <p>Currently, I have <code>/^[a-z0-9]{32}$/i</code></p>