diff between dates

<?php /** * @param $interval * @param $datefrom * @param $dateto * @param bool $using_timestamps * @return false|float|int|string */ function datediff($interval, $datefrom, $dateto, $using_timestamps = false) { /* $interval can be: yyyy - Number of full years q - Number of full quarters m - Number of full months y - Difference between day numbers (eg 1st Jan 2004 is "1", the first day. 2nd Feb 2003 is "33". The datediff is "-32".) d - Number of full days w - Number of full weekdays ww - Number of full weeks h - Number of full hours n - Number of full minutes s - Number of full seconds (default) */ if (!$using_timestamps) { $datefrom = strtotime($datefrom, 0); $dateto = strtotime($dateto, 0); } $difference = $dateto - $datefrom; // Difference in seconds $months_difference = 0; switch ($interval) { case 'yyyy': // Number of full years $years_difference = floor($difference / 31536000); if (mktime(date("H", $datefrom), date("i", $datefrom), date("s", $datefrom), date("n", $datefrom), date("j", $datefrom), date("Y", $datefrom)+$years_difference) > $dateto) { $years_difference--; } if (mktime(date("H", $dateto), date("i", $dateto), date("s", $dateto), date("n", $dateto), date("j", $dateto), date("Y", $dateto)-($years_difference+1)) > $datefrom) { $years_difference++; } $datediff = $years_difference; break; case "q": // Number of full quarters $quarters_difference = floor($difference / 8035200); while (mktime(date("H", $datefrom), date("i", $datefrom), date("s", $datefrom), date("n", $datefrom)+($quarters_difference*3), date("j", $dateto), date("Y", $datefrom)) < $dateto) { $months_difference++; } $quarters_difference--; $datediff = $quarters_difference; break; case "m": // Number of full months $months_difference = floor($difference / 2678400); while (mktime(date("H", $datefrom), date("i", $datefrom), date("s", $datefrom), date("n", $datefrom)+($months_difference), date("j", $dateto), date("Y", $datefrom)) < $dateto) { $months_difference++; } $months_difference--; $datediff = $months_difference; break; case 'y': // Difference between day numbers $datediff = date("z", $dateto) - date("z", $datefrom); break; case "d": // Number of full days $datediff = floor($difference / 86400); break; case "w": // Number of full weekdays $days_difference = floor($difference / 86400); $weeks_difference = floor($days_difference / 7); // Complete weeks $first_day = date("w", $datefrom); $days_remainder = floor($days_difference % 7); $odd_days = $first_day + $days_remainder; // Do we have a Saturday or Sunday in the remainder? if ($odd_days > 7) { // Sunday $days_remainder--; } if ($odd_days > 6) { // Saturday $days_remainder--; } $datediff = ($weeks_difference * 5) + $days_remainder; break; case "ww": // Number of full weeks $datediff = floor($difference / 604800); break; case "h": // Number of full hours $datediff = floor($difference / 3600); break; case "n": // Number of full minutes $datediff = floor($difference / 60); break; default: // Number of full seconds (default) $datediff = $difference; break; } return $datediff; } echo datediff('ww', '9 July 2003', '4 March 2004', false);