<?php function is_64bit() {
$int = "9223372036854775807";
$int = intval($int);
if ($int == 9223372036854775807) {
  /* 64bit */
  return true;
}
elseif ($int == 2147483647) {
  /* 32bit */
  return false;
}
else {
  /* error */
  return "error";
} }

if(is_64bit() === true) echo 'This version of PHP is 64bit!';
elseif(is_64bit() == "error") echo 'There was an unexpected error with the script.';
else echo 'This version of PHP is 32bit...';
?>