title: Regular Expressions: How to Express \w Without Underscore
body: <p>Is there a concise way to express: </p>
  
  <pre><code>\w but without _
  </code></pre>
  
  <p>That is, "all characters included in \w, except _" </p>
  
  <p>I'm asking this because I'm looking for the most concise way to express domain name validation. A domain name may include lowercase and uppercase letters, numbers, period signs and dashes, but no underscores. \w includes all of the above, plus an underscore. So, is there any way to "remove" an underscore from \w via regex syntax?</p>
  
  <p><strong>Edited:</strong> I'm asking about regex as used in PHP. </p>
  
  <p>Thanks in advance! </p>