Exemplo de array_chunk

gistfile1.php

<div class="carousel-inner">
<div class="item">
	    <?php
		$input_array = array('a', 'b', 'c', 'd', 'e');
		$carousel = array_chunk($input_array, 2);
		foreach($carousel as $c):
	    ?>
        <div class="row">
				<?php foreach($c as $item):?>
                <div class="col-md-3"></div>
				<?php endforeach?>
        </div>
		<?php endforeach?>
</div>
</div>