title: How to disallow "." (dot) as first character in regular expressions
body: <p>I want to create to regular expression that allows all combinations of characters and digits and also dots but not a dot at the beginning. So valid strings could be "1.2.3" or "1.b.34d" or something. But I want to disallow strings like "." or ".1.2.3".</p>
  
  <p>I'm trying with </p>
  
  <pre><code>[^.]{0,1}[ a-zA-Z_\\-\\.0-9]*
  </code></pre>
  
  <p>but this doesn't work. Anyone any better idea?</p>