Time difference not working when year changes - php

Question

I have a script that was working, well is working but not properly. The function is suppose to work out the time difference between two dates/times.
The First date is the Current Date and Time (Date + Hr:Min) and the second date is chosen by a user.
The purpose is to show error when the current date/time is within 24 hours from the user chosen date. i.e. if today is 23/20/2012 16:00 and the user chooses 24/10/2012 15:00 (this mean its within 24 hours) but if user chooses 26/10/2012 19:00 then its passed 24 hours.
Now this works fine but when the date changes its year (when user selected any date after 31st Dec 2012.. it assumes its still within 24 hours.. and im quite baffled how this happens.. can anyone shed some light what I've done wrong?
$dt = $_GET['dt']; $tm = $_GET['tm'];
// Current Date an time (Hrs & Mins)
$date1 = date("Y-m-d H:i");
// Chosen Date/Time
$date2 = date("Y-m-d", strtotime( "$dt" ) );
$diff = strtotime($date2." $tm") + - strtotime($date1);
if($diff/3600 < 24)
echo "0";
else
echo "1";
The following is the corresponding Ajax that makes th call
function getAjaxTime()
{
xmlHttp=GetXmlHttpObject();
if (xmlHttp==null)
{
alert ("Your browser does not support AJAX!");
return;
}
dt = document.frm.arrival_date.value;
tm = document.frm.arrival_hour.value +':'+document.frm.arrival_min.value;
xmlHttp.open("GET","<?php echo $base_dir;?>/admin/get/timediff.php?dt="+encodeURI(dt)+"&tm="+encodeURI(tm),false);
xmlHttp.send(null);
return xmlHttp.responseText;
}

Answer 1

I would try something like this:
function isDateWithin24Hours($targetDate, $currentDate = 'now') {
$targetDate = new DateTime($targetDate);
$currentDate = new DateTime($currentDate);
$interval = $targetDate->diff($currentDate);
//%a = total number of days
if ($interval->format('%a') > 1) {
return (int) false;
}
return (int) true;
}
echo isDateWithin24Hours('2012-10-24 19:00:00');
echo isDateWithin24Hours('2012-10-24 19:00:00', '2012-10-23 18:00:00');

Answer 2

According to the php manual - http://us3.php.net/manual/en/datetime.formats.date.php - your date is not a valid format:
24/10/2013 // with / as deliminators
These would be valid
24-10-2013 // with - as deliminators
10/24/2013 // with / as deliminators and as m/d/Y
Update-
Also, the following format is invalid in strtotime & date-
Thursday, 10 May, 2012 00:30
But this would be valid -
Thursday, May 10, 2012 00:30
Update #2
In fact once your $_GET['dt'] is in a valid php format, you could simplify your code to-
$dt = $_GET['dt']; $tm = $_GET['tm'];
// Current Date an time (Hrs & Mins)
$date1 = date("Y-m-d H:i");
$diff = strtotime($dt." ".$tm) + - strtotime($date1);
if($diff/3600 < 24)
echo "0";
else
echo "1";