title: Regex for numbers without dots
body: <p>I need a regular expression that accepts only integer numbers like this:</p>
  
  <pre><code>12 valid output 12
  (12) valid output 12
  [12] valid output 12
  12foo valid output 12
  12. not valid
  .12 not valid
  12.12 not valid
  </code></pre>
  
  <p>I have something like this:</p>
  
  <pre><code>^(?![.])\d+(?![.])
  </code></pre>