使用PHP每12小时在网站上交换图像的最简单方法

Question

I haven't coded in a while and I'm trying to find the easiest solution to this problem.

I have 20+ images on the server (labelled 1.png, 2.png, 3.png, etc.) and I'm using PHP to render three of them to my website at a time.

All I want is to make it so every twelve hours a new image replaces one of the old images. So for example it starts by rendering images 1, 2 and 3 and after twelve hours it switches to 2, 3 and 4.

What's the best way to achieve this effect?

Answer 1

This can be done in simple PHP (since you mentioned PHP).

$numOfImages = 20;
$unit = date('j') * 2; // Day of the month, doubled to simulate chunks of 12 hours.
if (date('G') < 12) { // Hours 0 - 23
    $unit--;
}

$image1 = $unit % $numOfImages;
$image2 = ($unit + 1) % $numOfImages;
$image3 = ($unit + 2) % $numOfImages;

var_dump($image1);
var_dump($image2);
var_dump($image3);