Look:
<?PHP

// return 4.1
print (float)PHP_VERSION;

$v = 4.1.4;
// return 4.1
print (float)$v;
?>

If someone wants to compare the versions of PHP, so he need to create a preg-like routine to change the string of PHP version to double numbers.

So, you can rewrite in C the phpversion to

function phpversion($withFloat = FALSE) {
  if ($withFloat == TRUE) {
    return 4.14;
  }
  return "4.1.4";
}

So, if someone want a float number, he will call phpversion(1); 

<?PHP

// output 4.14
print phpversion(1);

// output 4.1.4
print phpversion();
?>

Thanx.