Codeigniter - Inserting Ads after each x rows - codeigniter

Question

I want to insert advertisements after each X rows returned from database.
My Controller looks like this:
class Home extends CI_Controller {
public function __construct(){
parent::__construct();
$this->load->database();
$this->load->library('parser');
$this->load->helper('url');
$this->load->helper('download');
$this->load->model('Categorii');
$this->load->model('Comentarii');
}
public function index($pages = ""){
$c_ar = $this->Categorii->iaCategorii();
$sql = (!empty($pages)) ? "SELECT * FROM bancuri WHERE categorie = '" . $c_ar[$pages] . "'" : "SELECT * FROM bancuri";
$dbQ = $this->db->query($sql);
$renderData = array("bancuri" => $dbQ->result_array(), "ad" => "<img src='http://placehold.it/350x150'>"); //Se stocheaza datele intr-o matrice
$this->parser->parse('pages/bancuri',$renderData);
}
And view looks like this:
<div class="col-lg-8 col-sm-12 col-xs-12">
{bancuri}
{ad}
<div class="corgi_feed_well">
<div class="individual_feed_item">
<div class="feed_item">
<div class="feed_body">
<div class="row">
<!--
<audio controls>
<source src="<?php echo $this->config->item('base_url'); ?>resources/mp3/{mp3}" type="audio/mpeg">
</audio>
-->
</div>
<div class="row">
<div class="feed_profile_pic">
<span class="label label-info">Rating: {rating}</span>
<div class="clearfix"> </div>
<button type="button" class="btn btn-success">Like</button>
</div>
<div class="feed_text">
<p class="well">{banc}</p>
</div>
</div>
</div>
<div class="comment_area">
<p>Adauga un comentariu</p>
<form>
<textarea rows="3" class="span6"></textarea><br/>
<input type="submit" class="btn" />
</form>
</div>
<hr class="feed_hr" />
<div class="bottom_meta">
<div class="row">
<div class="bottom_left">
<div class="share_wrapper">
<div class="share"><i class="icon-heart"></i></div>
<div class="share_hidden">
<ul class="hover_heart">
<span class="internal_heart"><i class="icon-heart"></i> Trimite bancul pe</span>
<div class="social_links">
<li><span><i class="icon-twitter"></i> Twitter</span></li>
<li><span><i class="icon-facebook"></i> Facebook</span></li>
<li><span><i class="icon-pinterest"></i> Pinterest</span></li>
</div>
</ul>
</div>
</div>
</div>
<div class="bottom_left">
Descarca <span class="label label-primary">{descarcari} descarcari</span>
{comentarii} comentarii<br>
</div>
<div class="bottom_right">
{autor} <span>|</span> Adauga comentariu <span>|</span> {data}
</div>
</div>
</div>
</div>
</div>
</div>
{/bancuri}
The problem is that at the moment, it displays the ad (simple image atm) for every database row.

Answer 1

Regardless of the code you posted, In short, you just add a counter and use modulo.
so something like
$arr = range('a','z');
$n = 0;
foreach ($arr as $item)
{
if($n % 4 ==0) // 4 equals to the interval between ads
echo 'print banner';
$n++ ;
}
this will print an ad, or whatever you want, every 4 lines, play around with the numbers as you see fit and add a zero check if you don't like ads to appear in the first line.