loop index

<div class="row">
    <?php
    if(have_posts()) {
        while (have_posts()) {
            the_post(); ?>
            <div class="col-xs-6 col-lg-4">
                <?php
                the_title('<h2>', '</h2>');
                the_post_thumbnail('full', array('class' => 'img-responsive'));
                the_excerpt('<p>', '</p>'); ?>
                <p>
                    <a href="<?php the_permalink(); ?>" class="btn btn-default" role="button">Lire la suite »</a>
                </p>
            </div>
        <?php }
    } ?>
</div>