title: Multiple Conditions in Validation Regex
body: <p>I am more or less a regex novice. I tried to get the following conditions into a regex:</p>
  
  <ul>
  <li>No White Space at the beginning and at the end of a string</li>
  <li>Allow all digits</li>
  <li>Allow spaces, points, brackets, plus and minus</li>
  </ul>
  
  <p>Resulted in the following regex: </p>
  
  <pre><code>^\S[\d\/. ()\-+]*\S$
  </code></pre>
  
  <p>But now i try to apply two more conditions: </p>
  
  <ul>
  <li>Allow only one or two +</li>
  <li>Allow only one ( and one )</li>
  </ul>
  
  <p>My problem is how to merge those two conditions into the existing regex string above cuz excluding + <code>[+]{1,2}</code> and () <code>[(]{1} [)]{1}</code> doesn't make much sense cuz i try to make general statements in no particular order so that i would be able to chain it. Thanks Ralf </p>