title: Regex matching a non-empty string that is not equal to certain value
body: <p>I'm trying to write a regex to match any string that is not empty or equals to  <code>www</code>.</p>
  
  <p>Example:</p>
  
  <pre><code>www =&gt; don't match
  ww =&gt; match
  adwww =&gt; match
  wwwad =&gt; match
  abcde =&gt; match
  </code></pre>
  
  <p>My regex:</p>
  
  <pre><code>(.+)(www)
  </code></pre>
  
  <p>How  can I fix my regex?</p>