insert ad codes after first, second or nth post. http://wpsites.org/?p=10364/

add_action.php

<?php
function insert_between_posts( $post ) {
    global $wp_query;
 
    // Check if we're in the right template
    if ( ! is_home() )
        return;
 
    // Check if we're in the main loop
    if ( $wp_query->post != $post )
        return;
 
    // Check if we're at the right position
    if ( 1 != $wp_query->current_post )
        return;
 
    // Display the banner
    echo '<div>Some banner</div>';
}
add_action( 'the_post', 'insert_between_posts' );
?>

twenty-thirteen-loop.php

<?php if ( have_posts() ) : ?>
 
<?php /* The loop */ ?>
<?php while ( have_posts() ) : the_post(); ?>
    <?php get_template_part( 'content', get_post_format() ); ?>
<?php endwhile; ?>
<?php else : ?>
    <?php get_template_part( 'content', 'none' ); ?>
<?php endif; ?>

variable-count.php

<?php if ( have_posts() ) : $count=0; ?>
 
<?php /* The loop */ ?>
<?php while ( have_posts() ) : the_post(); $count++; ?>
    <?php get_template_part( 'content', get_post_format() ); ?>
    <?php if ($count == 2) : ?>
        Ad Codes after 2nd post
    <?php endif; ?>
<?php endwhile; ?>
 
<?php else : ?>
    <?php get_template_part( 'content', 'none' ); ?>

wp-query-full.php

<?php if ( have_posts() ) : ?>
 
<?php /* The loop */ ?>
<?php while ( have_posts() ) : the_post(); ?>
    <?php get_template_part( 'content', get_post_format() ); ?>
    <?php if ($wp_query->current_post == 1) : ?>
        Ad Codes after 2nd post
    <?php endif; ?>
<?php endwhile; ?>
 
<?php else : ?>
    <?php get_template_part( 'content', 'none' ); ?>
<?php endif; ?>

wp-query.php

<?php if ($wp_query->current_post == 1) : ?>
    Ad Codes after 2nd post
<?php endif; ?>