計算2000年01月01日起到指定日的天數

這是一個計算2000年01月01日起到指定日的天數的函數
<br>
(算頭也算尾)日期格式為：YYYY-MM-DD
<br>


<?php
// 計算從2000年01月01日開始到某日的天數

function cal_start2end($end_day,$start_day)
{


$start_day=ereg_replace("-","",$start_day);
$end_day=ereg_replace("-","",$end_day);


if($end_day>=$start_day)
{ // 截止日期大於開始日期
if(substr($end_day,0,4)==substr($start_day,0,4))
{

if( is_int(substr($end_day,0,4)/4) )
$leap_day=29; //leap year
else
$leap_day=28;


// //同一年

if(substr($end_day,4,2)==substr($start_day,4,2))
{
// the same month
$endday_from_startday=$end_day-$start_day 1;

}
else
{
// not same month


switch (substr($end_day,4,2))
{
case "01":
$endday_from_newyear=substr($end_day,6,2) 1;
break;
case "02":
$endday_from_newyear=substr($end_day,6,2) 31;
break;
case "03":
$endday_from_newyear=substr($end_day,6,2) $leap_day 31;
break;
case "04":
$endday_from_newyear=substr($end_day,6,2) 1 $leap_day 31*2;
break;
case "05":
$endday_from_newyear=substr($end_day,6,2) 1 $leap_day 31*2 30;
break;
case "06":
$endday_from_newyear=substr($end_day,6,2) 1 $leap_day 31*3 30;
break;
case "07":
$endday_from_newyear=substr($end_day,6,2) 1 $leap_day 31*2 30*2;