Changing HTML structure according to counter - php

Question

I have an HTML structure that I need to dynamically output.
I am using a counter within my loop to check for the first post, and applying the class headline-big and m-grid-item for the first post. Then I'm applying the second class headline-scroll for the subsequent posts.
The problem is, the 2nd, 3rd and 4th posts are not being nested inside headline-scroll they are each getting their own div.headline-scroll which is messing up site.
I need the 2nd, 3rd and 4th posts to be nested inside a single div.headline-scroll instead of each one of them being nested under a separate one.
This is the HTML for structure
<!-- / 1ST POST -->
<div class="headline-big">
<div class="m-grid-item">
...
</div>
</div>
<!-- / END OF FIRST POST -->
<!-- / 2ND, 3RD AND 4TH POST - ALL NESTED INSIDE div.headline-scroll -->
<div class="headline-scroll">
<!-- / 2ND POST -->
<div class="m-grid-item -medium">
...
</div>
<!-- / END OF 2ND POST -->
<!-- / 3RD POST -->
<div class="m-grid-item -small">
...
</div>
<!-- / END OF 3RD POST -->
<!-- / 4TH POST -->
<div class="m-grid-item -small">
...
</div>
<!-- / END OF 4TH POST -->
</div>
And this is the PHP
if ( $featured->have_posts() ) {
$i = 0;
while ( $featured->have_posts() ) {
$featured->the_post();
if ( $i == 0 ) :
?>
<div class="headline-big">
<div class="m-grid-item">
<?php endif; ?>
<?php if ( $i != 0 ) : ?>
<div class="headline-scroll">
<div class="m-grid-item -medium">
<?php endif; ?>
<?php the_title(); ?>
</div>
</div>
<?php $i++;
}
} else {
echo 'Add some posts';
}

Answer 1

I'm not sure if I could be able to answer your question well. But this is how I understand. If there is a question, please let me know and I will modify.
if ( $featured->have_posts() ) {
$i = 1;
while ( $featured->have_posts() )
{
$featured->the_post();
if( $i == 1)
{
?>
<div class="headline-big">
<div class="m-grid-item">
<?php the_title(); ?>
</div>
</div>
<div class="headline-scroll">
<?php
}
else
{
$small = array(3,4); //list of small classes
$class = ( in_array($i, $small)) ? '-small' : '-medium';
<div class="m-grid-item <?php echo $class; ?>">
<?php the_title(); ?>
</div>
<?php
}
$i++;
}
echo '</div><!-- end of headline-scroll -->';
} else {
echo 'Add some posts';
}

Answer 2

I've simplified it here with if conditions.
If it's the first post, create the headline-big div.
If it's the second post, create the headline-scroll div and the medium class div.
For all subsequent posts, just use the small div. Finally, outside the while loop, if we had more than 1 post, we need to add a closing div to close off the headline scroll.
if ( $featured->have_posts() ) {
$i = 0;
while ( $featured->have_posts() )
{
$featured->the_post();
if( $i == 0)
{
?>
<div class="headline-big">
<div class="m-grid-item">
<?php the_title(); ?>
</div>
</div>
<?php
}
else if($i == 1)
{
?>
<div class="headline-scroll">
<div class="m-grid-item -medium">
<?php the_title(); ?>
</div>
<?php
}
else
{
<div class="m-grid-item -small">
<?php the_title(); ?>
</div>
}
$i++;
}
if($i > 1){
?>
</div><!-- end of headline-scroll -->
<?php
}
} else {
echo 'Add some posts';
}

Answer 3

You never closed many of your DIV tags, and you were opening your div.headline-scroll inside a loop, so you were bound to get more than one. Try this instead maybe? Consistent indent and minimal PHP in your HTML will make things easier to debug, though you're hamstrung by Wordpress' awful functions.
<?php if (!$featured->have_posts()):?>
<p>Add some posts!</p>
<?php else: $i = 0; while ($featured->have_posts()): $featured->the_post();?>
<?php if (!$i):?>
<div class="headline-big">
<div class="m-grid-item">
<?php the_title(); ?>
</div>
</div>
<div class="headline-scroll">
<?php else:?>
<div class="m-grid-item -medium">
<?php endif; ?>
<?php the_title(); ?>
</div>
<?php $i++; endwhile;?>
</div>
<?php endif?>