inserting divs after other divs via PHP - php

Question

I have a loop code within Wordpress that displays all of my wordpress posts / divs and it looks like this:
<?php if ( have_posts() ) : ?>
<?php while ( have_posts() ) : the_post(); ?>
Then of course within that loop, there are my divs that the posts are in and then some end php code.. but here is what I want to do, how I did it, and why it didn't work.
I have about 60 posts on my mainpage with all the same div classes for each posts (of course) and I wanted to insert other divs before or after some of my post divs. And the way I went about doing this was pretty idiotic looking back.
I used CSS's nth-child to select my div posts, then give them margins or clears to make room for the other divs that I was going to insert. So for example, I'd have 60 posts / divs, 5 divs per row.. on the 10th post, I'd give it say a margin-left of however many pixels to make room for the div that needed to be inserted within these posts. Then when it came down to insert the div into the open spot, I'd float it right (because the div needed to be inserted on the right) and also a margin-top of however many pixels until it fit correctly into the open spot.
I thouht this worked correctly, but since my post divs width's are percentages and not pixels (my posts are thumbnails that need to be rescaled on resolution, so I used percentages), the divs that were inserted within my posts would not be in the correct spot when the window changed size, or when being viewed on a different resolution... so what did I do? Change all of the margin values for each div that need to be inserted beside these posts into percentages instead of pixels... This almost worked.. the only problem was that when you rescaled your browser, the divs that were inserted into my posts would move up or down 5-20 pixels.. which sucks!
Then later today, I had an epiphany.. and it was to use PHP to insert the divs within these posts instead of my stupid CSS ideology, I have no idea how it would be done, but I do think it's possible for some strange reason.
So what I would need to do would be insert these div classes called "doublearticlewrapperad" amongst these other div classes that are posts.. and these post classes are called "doublearticlewrapper". I would like to be able to position my doublearticlewrapperad div classes amongst the other doublearticlewrapper loop posts / div classes. So say I wanted to insert a doublearticlewrapperad div after the 6th, 29th and 40th doublearticlewrapper post div's.. I would like to be able to do that with ease.. if it's even possible.
Just to clear up any confusion..
doublearticlewrapperad = divs I would like to insert after the div classes that get displayed via my WordPress Loop.. and
articlewrapperad= divs that are displayed as posts via my wordpress loop.
If there is any way to do this I thought php would be the proper way, but if it turns out I am wrong and there is an alternative method or different code to do this.. please let me know. And guys, any help would truly truly be appreciated, I really mean it.

Answer 1

Try this bud!
$count = 0;
while ( have_posts() ) {
if ( ($count % 9) == 0 ) { //this will show anything you add on the condition in every 9th posts.
//code to output your doublearticlewrapperad should go here
}
// output the post
the_post();
$count++;
}
Cheers!

Answer 2

I think something like the following should work. Note that I removed the if statement you had, which was pretty useless, as you then repeat the check with the while statement.
$insert_after = array(6,29,40);
$post_count = 0;
while ( have_posts() ) {
if (in_array($post_count, $insert_after)) {
//code to output your doublearticlewrapperad should go here
}
// output the post
the_post();
$post_count++;
}