Share PHP code for calculating the number of days between two dates, _PHP tutorial

<&#63;php
$date1 = date( 'Y-m-d' );
$date2 = "2015-12-04";
$diff = abs(strtotime($date2) - strtotime($date1));
$years = floor($diff / (365*60*60*24));
$months = floor(($diff - $years * 365*60*60*24) / (30*60*60*24));
$days = floor(($diff - $years * 365*60*60*24 - $months*30*60*60*24)/ (60*60*24));
printf("%d years, %d months, %d days\n", $years, $months, $days);
-------------------------------------------------------- OR
$date1 = new DateTime("2007-03-24");
$date2 = new DateTime("2009-06-26");
$interval = $date1->diff($date2);
echo "difference " . $interval->y . " years, " . $interval->m." months, ".$interval->d." days "; 
// shows the total amount of days (not divided into years, months and days like above)
echo "difference " . $interval->days . " days ";
-------------------------------------------------------- OR  
  
/**
 * Calculate differences between two dates with precise semantics. Based on PHPs DateTime::diff()
 * implementation by Derick Rethans. Ported to PHP by Emil H, 2011-05-02. No rights reserved.
*/
function _date_range_limit($start, $end, $adj, $a, $b, $result)
{
 if ($result[$a] < $start) {
  $result[$b] -= intval(($start - $result[$a] - 1) / $adj) + 1;
  $result[$a] += $adj * intval(($start - $result[$a] - 1) / $adj + 1);
 }
 if ($result[$a] >= $end) {
  $result[$b] += intval($result[$a] / $adj);
  $result[$a] -= $adj * intval($result[$a] / $adj);
 }
 return $result;
}
function _date_range_limit_days($base, $result)
{
 $days_in_month_leap = array(31, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
 $days_in_month = array(31, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
 _date_range_limit(1, 13, 12, "m", "y", &$base);
 $year = $base["y"];
 $month = $base["m"];
 if (!$result["invert"]) {
  while ($result["d"] < 0) {
   $month--;
   if ($month < 1) {
    $month += 12;
    $year--;
   }
   $leapyear = $year % 400 == 0 || ($year % 100 != 0 && $year % 4 == 0);
   $days = $leapyear &#63; $days_in_month_leap[$month] : $days_in_month[$month];
   $result["d"] += $days;
   $result["m"]--;
  }
 } else {
  while ($result["d"] < 0) {
   $leapyear = $year % 400 == 0 || ($year % 100 != 0 && $year % 4 == 0);
   $days = $leapyear &#63; $days_in_month_leap[$month] : $days_in_month[$month];
   $result["d"] += $days;
   $result["m"]--;
   $month++;
   if ($month > 12) {
    $month -= 12;
    $year++;
   }
  }
 }
 return $result;
}
function _date_normalize($base, $result)
{
 $result = _date_range_limit(0, 60, 60, "s", "i", $result);
 $result = _date_range_limit(0, 60, 60, "i", "h", $result);
 $result = _date_range_limit(0, 24, 24, "h", "d", $result);
 $result = _date_range_limit(0, 12, 12, "m", "y", $result);
 $result = _date_range_limit_days(&$base, &$result);
 $result = _date_range_limit(0, 12, 12, "m", "y", $result);
 return $result;
}
/**
 * Accepts two unix timestamps.
 */
function _date_diff($one, $two)
{
 $invert = false;
 if ($one > $two) {
  list($one, $two) = array($two, $one);
  $invert = true;
 }
 $key = array("y", "m", "d", "h", "i", "s");
 $a = array_combine($key, array_map("intval", explode(" ", date("Y m d H i s", $one))));
 $b = array_combine($key, array_map("intval", explode(" ", date("Y m d H i s", $two))));
 $result = array();
 $result["y"] = $b["y"] - $a["y"];
 $result["m"] = $b["m"] - $a["m"];
 $result["d"] = $b["d"] - $a["d"];
 $result["h"] = $b["h"] - $a["h"];
 $result["i"] = $b["i"] - $a["i"];
 $result["s"] = $b["s"] - $a["s"];
 $result["invert"] = $invert &#63; 1 : 0;
 $result["days"] = intval(abs(($one - $two)/86400));
 if ($invert) {
  _date_normalize(&$a, &$result);
 } else {
  _date_normalize(&$b, &$result);
 }
 return $result;
}
$date = "2014-12-04 19:37:22";
echo '<pre class="brush:php;toolbar:false">';
print_r( _date_diff( strtotime($date), time() ) );
echo '