date diff in php

it is a common task to determine the number of days from one given date to another. and with php there are a number of ways to tackle this. one of the easiest i have found is to use the gregoriantojd() function.

the gregoriantojd() function requires three parameters: month, day, year. it will return you an integer containing the julian day. once you have converted each date, it is then a simple matter of subtracting one from the other.
this will find the number of days until january 1, 2010:

$today = date("Y-m-j");
$days = datediff($today, '2010-01-01');
echo "days until january 1, 2010 is : " . $days;

now call the datediff function which calculates the number of days:

function dateDiff($startDate, $endDate)
{
    $date1=explode('-', $startDate);
    $date2=explode('-', $endDate);
    $startDate=gregoriantojd($date1[1], $date1[2], $date1[0]);
    $endDate=gregoriantojd($date2[1], $date2[2], $date2[0]);
    return $endDate - $startDate;
}