Adding PHP code in extension after every nth list element in TYPO3 - php

Question

I'm using old fashion way (kickstarter) to build extension in TYPO3. I would like to ad some PHP code after third element of list, but I really don't know how to do this.
My code looks like that:
protected function makeList($res) {
$items = array();
// Make list table rows
while (($this->internal['currentRow'] = $GLOBALS['TYPO3_DB']->sql_fetch_assoc($res)) !== FALSE) {
$items[] = $this->makeListItem();
}
$out = '<div' . $this->pi_classParam('listrow') . '>list items</div>';
return $out;
}
And:
protected function makeListItem() {
$out = 'list item details';
return $out;
}

Answer 1

If I understood correctly, you would need something like this:
protected function makeList($res) {
$items = array();
// Make list table rows
$i = 0;
$out = '<div' . $this->pi_classParam('listrow') . '>';
while (($this->internal['currentRow'] = $GLOBALS['TYPO3_DB']->sql_fetch_assoc($res)) !== FALSE) {
$out .= $this->makeListItem();
$i++;
if ($i == 3) {
$out .= '<img src="whateverjpg">';
$i = 0; // if you want to do it every 3 images
}
}
$out .= '</div>';
return $out;
}