how to define category loop last class in the third

Question

on my page category.php file i'm using product listing,

product block loop is ,

product-block , product-block , product-block last

last class no margin-left,

how to define third product "last class" in the category loop?

my content.php

<div class="goods_list catalog_goods">
            <div class="goods_item">
              <div class="foto">
                <div class="shadow"></div><?php the_excerpt(); ?>
                <a href="<?php the_permalink(); ?>"><?php echo get_the_post_thumbnail($id,  array(220,220)); ?></a>
              </div>
              <div class="bot">
               <a href="<?php the_permalink(); ?>" rel="bookmark"><?php the_title(); ?></a>

                <div class="stars"></div>

                <div class="order">
                  <a class="but_buy"><i class="icon-shopping-cart icon-large"></i> &nbsp;Buy </a>
                  <span class="price">$45.00</span>
                </div>
              </div>
            </div>
          </div>

i must define third div good_list catalog_goods last

my category.php file

  <div class="catalog_right">
        <div class="catalog_goods_block">


        <?php if ( have_posts() ) : ?>



            <?php twentyeleven_content_nav( 'nav-above' ); ?>

            <?php /* Start the Loop */ ?>

            <?php while ( have_posts() ) : the_post(); ?>
            <?php
                    /* Include the Post-Format-specific template for the content.
                     * If you want to overload this in a child theme then include a file
                     * called content-___.php (where ___ is the Post Format name) and that will be used instead.
                     */
                    get_template_part( 'content', get_post_format() );
                ?>

            <?php endwhile; ?>

Answer 1

You can do with php modulus % operator.

Lets work with your code.

    <?php if ( have_posts() ) : ?>



        <?php twentyeleven_content_nav( 'nav-above' ); ?>

        <?php /* Start the Loop */ ?>
        <?php $count = 1; ?>
        <?php while ( have_posts() ) : the_post(); ?>
        <?php
                /* Include the Post-Format-specific template for the content.
                 * If you want to overload this in a child theme then include a file
                 * called content-___.php (where ___ is the Post Format name) and that will be used instead.
                 */
                get_template_part( 'content', get_post_format() );
            ?>

        <?php endwhile; ?>

Add $count=1

Then in your content.php:

    <?php
        global $count;
        if ($count % 3 === 0) {
            $no_margin = 'last';
        }
    ?>    
    <div class="goods_list catalog_goods <?php echo $no_margin; ?>">
                    <div class="goods_item">
                      <div class="foto">
                        <div class="shadow"></div><?php the_excerpt(); ?>
                        <a href="<?php the_permalink(); ?>"><?php echo get_the_post_thumbnail($id,  array(220,220)); ?></a>
                      </div>
                      <div class="bot">
                       <a href="<?php the_permalink(); ?>" rel="bookmark"><?php the_title(); ?></a>

                        <div class="stars"></div>

                        <div class="order">
                          <a class="but_buy"><i class="icon-shopping-cart icon-large"></i> &nbsp;Buy </a>
                          <span class="price">$45.00</span>
                        </div>
                      </div>
                    </div>
                  </div>
<?php ++$count; ?>

Make the $count variable global so it can be accessible.

Heres the main part

Remainder of $count divided by 3

and add:

<div class="goods_list catalog_goods <?php echo $no_margin; ?>">

echo $no_margin

At the last add:

<?php ++$count; ?>

so it will increment until the loop finishes.