任何人都可以解释这个PHP？

<ul class="top_ads">
    <?php
        $totalImages = 5;
        $all = range(1,$totalImages);
        shuffle($all);

        foreach ($all as $single) {
            echo "<li><a href='' /><img src='"; echo bloginfo('template_url') . "/images/ads/ad_0$single.png' alt='ad' /></li>";
        }
    ?>
</ul>

can anyone please explain bloginfo('template_url') within this php code? sorry, if it seems trivial to you. also the path "/images/ads/ad_0$single.png". I am learning php. Thank you.

Which function I need to use in place of bloginfo('template_url') if I do not use wordpress but php as a template engine? anyone helps me?

the function is randomizing 5 ads.
each ad has the name in: /images/ads/ad_01.png .. /images/ads/ad_05.png.

first the range (1, 5) makes an array {1,2,3,4,5} shuffle mixes it up so it looks more like {4,3,5,1,2} foreach ($all as $single) will call the echo statement for each of those numbers in the new order

bloginfo('template_url') is a function somewhere else in your code. it is outputting a template url path partial. most likely its something like /templates.

using chrome: you can figure that out by right clicking on one of these ads and choosing inspect element and find the exact url that is being built out.