title: How to check if string value returned from text input is integer
body: <p>I have a form where users search for keywords.</p>
  
  <p>I want to check if users submit a number (integer) instead of a keyword.</p>
  
  <p>I use this:</p>
  
  <pre><code>$keyword = $_REQUEST["keyword"];
  
  if (is_int($keyword)) {
    echo 'true';
  } else {
    echo 'false';
  }
  </code></pre>
  
  <p>but it always returns false even when the value submitted is integer.</p>