// initiate the default wordpress loop as usual
<?php if (have_posts()) : while(have_posts()) :
// set a count variable to increase with each loop
$i++;
// test the variable modulus against a zero value
// odd values return true, even values return false
// see proceding discussion for more information
if(($i % 2) == 0) :
// skip to next post if variable is an even number
$wp_query->next_post();
// display the post if variable is an odd number
else : the_post(); ?>
// open a division for the left column
<div id="left-column">
// display the title of the post
<h1><?php the_permalink(); ?></h1>
// display the post content
<?php the_content(); ?>
// close the division
</div>
// close the first if statement
<?php endif;
// close the loop
endwhile;
// if there are no posts that meet the criteria
else: ?>
// display some alternate content
<div>Alternate content</div>
// close the second if statement
<?php endif; ?>
// reset the count variable to zero
<?php $i = 0;
// reset the loop
rewind_posts(); ?>
// the second loop is essentially the same as the first
// the only difference is that we are testing the count variable against a non-zero value to display only even numbers
<?php if (have_posts()) : while(have_posts()) : $i++; if(($i % 2) !== 0) : $wp_query->next_post(); else : the_post(); ?>
// and of course a unique div id for the right column
<div id="right-column">
<h1><?php the_permalink(); ?></h1>
<?php the_content(); ?>
</div>
<?php endif; endwhile; else: ?>
<div>Alternate content</div>
<?php endif; ?>