title: Large hex values with PHP hexdec
body: <p>I have some large HEX values that I want to display as regular numbers, I was using hexdec() to convert to float, and I found a function on PHP.net to convert that to decimal, but it seems to hit a ceiling, e.g.:</p>
  
  <pre><code>$h = 'D5CE3E462533364B';
  $f = hexdec($h);
  echo $f .' = '. Exp_to_dec($f);
  </code></pre>
  
  <p>Output: 1.5406319846274E+19 = 15406319846274000000</p>
  
  <p>Result from calc.exe = 15406319846273791563</p>
  
  <p>Is there another method to convert large hex values?</p>