tempo fai trovai come open source la funzione DateDiff dell'ASP convertita in PHP per scopi didattici
Codice PHP:
function datediff($interval, $date1, $date2) {
$seconds = $date2 - $date1;
switch ($interval) {
case "y": // years
list($year1, $month1, $day1) = split('-', date('Y-m-d', $date1));
list($year2, $month2, $day2) = split('-', date('Y-m-d', $date2));
$time1 = (date('H',$date1)*3600) + (date('i',$date1)*60) + (date('s',$date1));
$time2 = (date('H',$date2)*3600) + (date('i',$date2)*60) + (date('s',$date2));
$diff = $year2 - $year1;
if($month1 > $month2) {
$diff -= 1;
} elseif($month1 == $month2) {
if($day1 > $day2) {
$diff -= 1;
} elseif($day1 == $day2) {
if($time1 > $time2) {
$diff -= 1;
}
}
}
break;
case "m": // months
list($year1, $month1, $day1) = split('-', date('Y-m-d', $date1));
list($year2, $month2, $day2) = split('-', date('Y-m-d', $date2));
$time1 = (date('H',$date1)*3600) + (date('i',$date1)*60) + (date('s',$date1));
$time2 = (date('H',$date2)*3600) + (date('i',$date2)*60) + (date('s',$date2));
$diff = ($year2 * 12 + $month2) - ($year1 * 12 + $month1);
if($day1 > $day2) {
$diff -= 1;
} elseif($day1 == $day2) {
if($time1 > $time2) {
$diff -= 1;
}
}
break;
case "w": // weeks
// Only simple seconds calculation needed from here on
$diff = floor($seconds / 604800);
break;
case "d": // days
$diff = floor($seconds / 86400);
break;
case "h": // hours
$diff = floor($seconds / 3600);
break;
case "i": // minutes
$diff = floor($seconds / 60);
break;
case "s": // seconds
$diff = $seconds;
break;
}
return $diff;
}