Setting a time and date and adding to it in PHP - php

Question

Basically am trying to set a time and a date in PHP then set a time gap which will range between minutes, loop through between a start time and end time echoing something out for each one. Have tried loads of different ways and cant seem to figure a way to set a date and add to it.
This seems the best script I have modified so far:
$minutes = 5;
$endtime = new DateTime('2012-01-01 09:00');
$newendtime = $endtime->format('Y-m-d H:i');
$timedate = new DateTime('2012-01-01 09:00');
while($stamp < $newendtime)
{
$time = new DateTime($timedate);
$time->add(new DateInterval('PT' . $minutes . 'M'));
$timedate = $time->format('Y-m-d H:i');
echo $timedate;
}

Answer 1

$minutes = 5;
$endtime = new DateTime('2012-01-01 09:00');
//modified the start value to get something _before_ the endtime:
$time = new DateTime('2012-01-01 8:00');
$interval = new DateInterval('PT' . $minutes . 'M');
while($time < $endtime){
$time->add($interval);
echo $time->format('Y-m-d H:i');
}

Answer 2

Do everything in seconds, and use php's time(), date(), and mktime functions.
In UNIX Time, dates are stored as the number of seconds since Jan 1, 1970.
You can render UNIX Timestamps with date().
$time = time(); // gets current time
$endtime = mktime(0,0,0, 1, 31, 2012); // set jan 31 # midnight as end time
$interval = 60 * 5; // 300 seconds = 5 minutes
while($time < $endtime){
$time += $interval;
echo date("M jS Y h:i:s a",$time) . "<br>"; // echos time as Jan 17th, 2012 1:04:56 pm
}
date reference:
http://us3.php.net/manual/en/function.date.php (includes superb date format reference too)
mktime reference: http://us2.php.net/mktime
time() only gets the current time, but just for kicks n' giggles: http://us2.php.net/time
And, it's super easy to store in a database!

Answer 3

This function will let you add date to your existing datetime. This will also preserves HH:MM:SS
<?php
function add_date($givendate,$day=0,$mth=0,$yr=0) {
$cd = strtotime($givendate);
$newdate = date('Y-m-d h:i:s', mktime(date('h',$cd),
date('i',$cd), date('s',$cd), date('m',$cd)+$mth,
date('d',$cd)+$day, date('Y',$cd)+$yr));
return $newdate;
}
?>
Usage:
add_date($date,12,0,0);
where $date is your date.