Number of intersections between 2 date ranges - php

Question

I have 2 date ranges in my Codeigniter App, and i want to calculate the number of days that intersects between those to ranges. any ideas?
Date1start = YYYY-MM-DD;
Date1end = YYYY-MM-DD;
Date2start = YYYY-MM-DD;
Date2end = YYYY-MM-DD;

Answer 1

Something like this should work
$datetimeStart1 = new DateTime('2015-12-10');
$datetimeEnd1 = new DateTime('2015-12-20');
$datetimeStart2 = new DateTime('2015-12-12');
$datetimeEnd2 = new DateTime('2015-12-28');
// following http://stackoverflow.com/questions/325933/determine-whether-two-date-ranges-overlap
if ($datetimeStart1 < $datetimeEnd2 && $datetimeEnd1 > $datetimeStart2) {
echo min($datetimeEnd1,$datetimeEnd2)->diff(max($datetimeStart2,$datetimeStart1))->days+1;
} else {
echo 'no overlap';
}
Demo: http://3v4l.org/9Pecb
Only for PHP 5.2
$datetimeStart1 = new DateTime('2015-12-10');
$datetimeStart1 = $datetimeStart1->format('U');
$datetimeEnd1 = new DateTime('2015-12-20');
$datetimeEnd1 = $datetimeEnd1->format('U');
$datetimeStart2 = new DateTime('2015-12-12');
$datetimeStart2 = $datetimeStart2->format('U');
$datetimeEnd2 = new DateTime('2015-12-28');
$datetimeEnd2 = $datetimeEnd2->format('U');
// following http://stackoverflow.com/questions/325933/determine-whether-two-date-ranges-overlap
if ($datetimeStart1 < $datetimeEnd2 && $datetimeEnd1 > $datetimeStart2) {
echo round(
((min($datetimeEnd1,$datetimeEnd2)) - (max($datetimeStart2,$datetimeStart1))) / (60*60*24)) + 1;
} else {
echo 'no overlap';
}
Demo: http://3v4l.org/a1WLk

Answer 2

Write it easy:
$datetimeStart1 = new DateTime('2015-12-10');
$datetimeEnd1 = new DateTime('2015-12-20');
$datetimeStart2 = new DateTime('2015-12-12');
$datetimeEnd2 = new DateTime('2015-12-28');
$start = max($datetimeStart2,$datetimeStart1);
$end = min($datetimeEnd1,$datetimeEnd2);
echo $end >= $start ? $end->diff($start)->days+1 : "no overlap";