change image in every three days using php - php

Question

I am creating a wordpress widget. This will allow user to upload the image url of eight different picture. Now I want to change the image everty three days and start from begining after eight one for infinite time.
I manage to get the start of the first image. let sat that is : 2014/07/28
I have applied this logic:
$date = $start_date;
$date = strtotime($date);
$date = strtotime("+3 day", $date);
$end_date = date('Y-m-d', $date);
$begin = new DateTime( $start_date );
$end = new DateTime('');
$end = $end->modify( '+1 day' );
$interval = new DateInterval('P1D');
$daterange = new DatePeriod($begin, $interval ,$end);
if($start_date <= $end_date && $end_date > date('Y-m-d'))
{
$image_number = 1;
}else{
$i = 1;
$j = 1;
foreach($daterange as $date){
if($i%3 == 0){
echo $image_number = $j;
$j++;
if($j > 8){
$j = 1;
}
}
$i++;
}
}
?>
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Can anybody tell me what is wrong with the code.
Thank you everybody in advance for your valuable time.

Answer 1

Alright so it seems you have 8 images named 1.jpg to 8.jpg
Every three days you want to change the image to the next, and when you are at 8, you want to go to 1.
I don't know if you have some kind of start date on which the images were uploaded, and I don't know if it matters to you.
Let's start out with an example in which viewing the image is tied to the date (and resets on the first of january)
##maybe you would like to set the timezone
##date_default_timezone_set('America/Los_Angeles');
$dayOfTheYear = date('z');
$iterationCount = ceil($dayOfTheYear / 3);
$numberForIteration = $iterationCount % 8;
echo '<img alt="" src="'.$numberForIteration.'.jpg" />';
## prints for example: <img alt="" src="6.jpg" />
We can build on this and have an option of a different start date, meaning that not january 1st, but another date is the start date.
## PHP Version should be above June 2012
$startDate = new DateTime("2014-07-01");
$currentDate = new DateTime();
$daysSinceStart = $startDate->diff($currentDate)->days;
$iterationCount = ceil($daysSinceStart / 3);
$numberForIteration = $iterationCount % 8;
echo '<img alt="" src="'.$numberForIteration.'.jpg" />';
Hope it helps.
David