title: cast a number from string to int would change the value in php
body: <p>I'm working on a project in PHP, and trying to use one of the parameters in <code>$_POST</code>, unfortunately I want to send the result to a web service, which only accepts the parameter as integer. So I have to cast the type with <code>(int)</code> but this work will change the value of parameter
  for instance its something like this:</p>
  
  <pre><code>$o =  4924869620;
  $c = (int) $o;
  </code></pre>
  
  <p>then c will have the value 629902324</p>
  
  <p>Why this thing happen? how can I keep the value the same?? I have also used <code>intval()</code> and it will also change the value </p>